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QUEENS BOROUGH (BLACKWELL'S ISLAND) BRIDGE, NEW YORK. 



How It is Done 

or, 
VICTORIES OF THE ENGINEER 



Describing in simple language how great Engineering 

Achievements in all parts of the world 

have been accomplished 



By 



ARCHIBALD WILLIAMS 

Author of " The Romance of Modern Invention, 

" How h is Made," 

•• How h Works," 

etc., etc. 



New York 
THOMAS NELSON AND SONS 

37 East 18th Street 



^v 



\<^ 



:^1 



LIBRARY of CONGRESS 
Two Cot'ies Received 

OCT 29 1908 

CLASS CL. XXC, No, 
COPY B. 



Copyright. 1908, 
By THOMAS NELSON AND SONS 




AUTHOE'S NOTE. 



My thanks are due to the following gentlemen for the help 
they have given me in the preparation of this volume, as 
regards both the letterpress and the illustrations : — 

Messrs. C. J. F. Pole; John Geo. Leigh; F. Everett; 
W. P. Devine; E. W. Dana; J. H. T. Tudsbery ; A. H. 
Owles. And to the following firms : — The Denver and Eio 
Grande Eailroad Co. ; Messrs. Stanley and Co. ; The 
Bucyrus Co., South Milwaukee; Messrs Brown, Lenox, 
and Co. ; Messrs. Hingley and Co., Netherton ; The Wall- 
send Slipway and Engineering Co. ; Messrs. Swan Hunter 
and Wigham Eichardson, Ltd. ; Messrs. Viekers Sons and 
Maxim; The Pennsylvania Steel Co.; Messrs. John A. 
Eoebling and Sons, New York; Sir John Aird and Co.; 
Messrs. Thos. Piggott and Co. ; Messrs. Mephan Ferguson, 
Ltd.; Messrs. Jas. Simpson and Co.; The Excelsior 
Wooden Pipe Co.; The Buckeye Traction Ditcher Co.; 
Messrs Lobnitz and Co., Eenfrew ; Messrs. S. Pearson and 
Son, Ltd. ; The Central London Eailway Co. ; The Penn- 
sylvania Eailroad Co. ; The IngersoU Sergeant Drill Co. ; 
The American Loco. Co. Also the proprietors of Cas- 
siers Magazine; the World's Work; the Scientific Amer- 
ican; Engineering ; The Engineer; and The Shipbuilder. 

I am under special obligations to my draughtsman, Mr. 
H. Ludar Lee, and to Mr. E. H. Fitchew, for the prepara- 
tion of many of the diagrams included in this book. 



CONTENTS. 



Chapter I.-RAILROAD ENGINEERING. 

The significance of the railroad — What the railroad engineer has to 
do — PreUminary operations — The reconnaissance — "Develop- 
ment " — HeUcal tunnels — Preliminary surveys — Levelling — 
Contours — The surveyor's life — Location survey — Ranging 
curves — The theodolite — Several methods of ranging described — 
Road constmjction — Record tracklaying — Cuttings and embank- 
ments — Blasting rock — A trestle through a lake — Snowsheds — 
Laying the track — Preparing the ties — Standard rails — Driving 
the last spike on the Canadian Pacific Railway — Rack railways 
— Jungfrau Railway — Pike's Peak Railway 15 

Chapter II.~A RAILWAY THROUGH THE SEA:— TRAIN 
FERRIES. 

The Florida Keys — A great project — Difficult surveying — Labor 
troubles — Embankments made by dredges — Vast quantities of 
materials transported by sea — A railway of viaducts — Work at 
Key West — A train ferry to Havana — Other train ferries — Sea 
ferries — How a train is embarked and landed — Danish ferries — 
Ferries on the Great Lakes — The Baikal 63 

Chapter III.— THE BUILDING OF A BIG SHIP. 

The ocean liner — Shipbuilding — Two mammoth vessels — Planning a 
ship — Sheer draught — Detail drawings — Experimental model — 
The building sheds — The structure of a ship — Keel, frames, 
floors, and other details — The skin of a ship — Shipwrights at 
work — Assembling the framework — The plating — Riveting — ■ 
Preparations for the launch — Moving and standing ways — 
Greasing the ways — The drags — The launch — The engines of the 
big ship — ^Huge turbines — Fitting out the ship — The official 
trials — Ruskin on ships 73 



CONTENTS. 
Chapter IV.— BRIDGE BUILDING. 

Bridge versus tunnel — The development of the bridsre — Plank bridge — 
The open-work girder or truss — ^The bowstring girder — The 
arch — The suspension bridge — The cantilever principle — De- 
velopment of same — Advantages of the cantilever 117 

Chapter v.— THE FOUNDATIONS OF A BRIDGE. 

Need for firm foundations— Three methods of obtaining them — The 
pneumatic caisson — Its use for the Forth Bridge piers — Sinking 
a caisson — The ejector — The hydrauUc spade — Filling-in a cais- 
son with concrete — Blasting — Deep work with the pneumatic 
caisson — "Caisson disease" — The deep, open caisson — Cofferdams 
— Pile-driving 131 

Chapter VI. -THE ERECTION OF A TRESTLE BRIDGE. 

Raising rersws girders building out — The Britannia Bridge — The Gokteik 
Viaduct, Burma — Transporting the parts froin Pennsylvania 
to Burma — Quick unloading — The beginning of the bridge — 
Lowering the parts into position — ^A tall tower — The value of 
organization . .144 

Chapter VII.— SUSPENSION BRIDGES. 

The great suspension bridges over the East River, New York — The 
Brooklyn Bridge — Its dimensions and carrying capacity — The 
cables of a suspension bridge — Problems of their formation — 
Constructing temporary foot-bridges across the river — Spinning 
the cable wires — How it is done — Clamping and covering the 
cables — The Manhattan Suspension Bridge — 23,000 miles of wire 
— Facts and figures 155 

Chapter VIIL-CANTILEVER BRIDGES: THE FORTH 
BRIDGE. 

A glimpse of the Forth Bridge — The cantilevers — The towers — 
Skewbacks — Balancing the arms— Facts and figures — Prepara- 
tions for erection — Making the tube' plates — Riveting — The rising 
platforms — Adjusting the columns — The top chords — Building 
the cantilever arms — Ticklish work — The suspended girders 
— Joining up — A dehcate operation — An exciting incident. . . .174 



\ 



CONTENTS. 
Chapter IX.— THE BLACKWELL'S ISLAND BRIDGE. 

The bridge — Its main features — Gigantic pins — How they put the 
bridge together — Huge stone supports — The island span — False- 
work^Twin travelhng cranes — Making the arms — The capacity 
of the bridge — A huge arch bridge — JuHus Caesar 191 

Chapter X.— A TERRIBLE DISASTER. 

The Quebec Bridge — Its huge span — Measurements — Erection — An 
ominous occurrence — The fall of the structure — A tragedy .... 203 

Chapter XL— THE DESIGNING OF DAMS. 

Great quantities of water wanted for towns, power, and irrigation — 
Storage necessary — The dam-builder's task — ^Classes of dams 
— Masonry dams — The earth dam — Some mathematical facts — ■ 
Centres of gravity and pressure — Further considerations — ^Distri- 
bution of pressure — Sir Benjamin Baker's model — Summary. . . 207 

Chapter XIL— THE BUILDING OF THE NEW CROTON 

DAM. 

The growth of New York's demand for water — The new dam; its 
great size — The Croton River — -Plan of operations — Diversion 
canal — Removing debris — Cutting the foundations — Dam origi- 
nally partly an earth dam — Laying the masonry — Stopping springs 
— Work in cold weather — The earth dam; grave doubts about 
its safety — Its removal decided upon — The spillway — Clearing 
the reservoir area — "Pointing" the dam — The dam completed.. 220 

Chapter XIII.— HOW THE NILE WAS CURBED. 

The valley of the Nile — The Delta Barrage — A failure — British engi- 
neers to the rescue — Further schemes — A great survey — The 
Assyut Barrage — Sir Benjamin Baker's account — Diverting the 
main channel — The great dam at Aswan — Original plans — A 
straight dam decided upon — The course of operations — Forming 
sudds — Pumping out the water — Rapid construction — The lock 
gates — The sluice gates — Raising the dam 235 

Chapter XIV.— SOME NOTABLE RESERVOIRS. 

The Catskill Reservoirs — Olive Bridge Dam — The reservoir — Other 
great storage schemes — The Wachusett Reservoir for Boston — 



CONTENTS. 

How Manchester, Liverpool, and Birmingham are supplied — An 
Australian dam — The Barren Jack scheme — An arch dam — Irri- 
gation projects — The Periyar, Tansa, Nira, Khadak\'aria, Mara- 
kanave, and Dhukwa dams — Irrigation work dams in the United 
States — A Mexican dam 259 

Chapter XV.— AQUEDUCTS. 

Roman aqueducts — -Their principle — The modern aqueduct — "Hy- 
drauhc gradient" — Balancing reservoirs — Siphons — Pipe- joints — 
Notable aqueducts — The New Croton described — The Catskill 
Aqueduct — A colossal enterprise — Enormous siphons — The Cool- 
gardie pipe hne — A novel kind of pipe — La>dng the pipe — Pump- 
ing the water — Charging the main — Wooden pipe-lines — Some 
striking examples — A clever piece of work, sliifting a pipe-Une — 
A curious excavating machine 272 

Chapter XVI.— CANALS AND WATERWAYS. 

Canals to the front again — The advantages of canals — Two classes 
of canals — Boat -raising de^'ices — The lock — Mechanical boat-lifts 
and inclines — Excavating operations — Dredges — Grabs — Steam 
shovels — Floating excavators — The bucket dredge — The suction 
• dredge — Protecting the banks — A huge mattress— Ship canals — 
The Suez Canal — The Manchester Ship Canal — The Kaiser Wilhelm 
Canal — Some American schemes — A great Canadian project — 
Its significance 304 

Chapter XVII.— THE PANAMA CANAL; IRRIGATION 
CANALS; A TUBE CANAL. 

An intolerable obstacle to shipping — M. Ferdinand de Lesseps forms 
a company to pierce the Isthmus of Panama — Difficulties en- 
countered — The French cede their rights to the United States — 
The present scheme — The Gatun Dam — Work in the Culebra 
cut — The Panama Canal the greatest of all engineering feats — 
Irrigation canals — A steel-lined canal at Kom Ombo — The Un- 
compahgre Valley project, Colorado — A long tunnel required — 
A projected tube canal over the Alps 333 

Chapter XVIII.— HARBOR WORKS. 

Artificial harbors — Force of waves — Types of breakwaters — Methods 
of construction — Building-out — Titan cranes — Gantry method — 




CONTENTS. 

The Dover harbor works — How the work was done — Block- 
making — Building the gantries— Preparing the ground — Diving 
bells — The island breakwater — The Admiralty pier extension — 
Aprons — Prince of Wales Pier 350 

Chapter XIX.— TUNNELS AND TUNNELLING. 

Tunnelling difficult and risky work — Roman tunnels — Explosives 
and the powder drill — The shield principle — Classes of tunnel- 
Ung — Mountain tunnels — Surveying — Transferring the centre 
line down a shaft — Operations underground — Methods of exca- 
vating — The Simplon Tunnel — The Brandt rock drill — ^Ventila- 
tion — Difficulties encountered and overcome — The headings meet 
— Accuracy of calculations — Other famous mountain tunnels — 
The Mont Cenis— The St. Gothard — The Arlberg — The cut-and- 
cover system — The longitudinal trench method — The transverse 
trench method 376 

Chapter XX.— SUBMARINE TUNNELS. 

The Severn tunnel — The shield system of tunnelling — Construction 
of the shield — The front-end, body, and tail — Shields with air- 
locks — The Rotherhithe tunnel — Sinking the shafts — Driving a 
"pilot" tunnel — The big shield at work — Advancing the shield — 
Guiding the shield — Accuracy with which the shield is steered 
— Some instances — Fighting water — Securing a tunnel with piles — 
Big tunnelling projects— -The Harlem River tunnel — Building 
the caisson — Constructing the tunnel under the caisson — An- 
other method tried successfully — The Detroit River tunnel — 
A double-barrelled tube sunk by sections — How it was done — 
Connecting up the sections — Covering the sections with con- 
crete 400 

Chapter XXL— MINING AND MINES. 

Various t5T)es of mines — Shaft sinking — The Kind-Chaudron system 
— The freezing process adopted for sinking through quicksands 
— Fitting up the shaft — Hoisting gear — ^Ventilation — Natural 
circulation of air — Furnace ventilation — Fan ventilation — Un- 
watering a mine — By tunnels — By siphons — By ejectors — By 
buckets — By pumps — Breaking ground — Underhand and over- 
hand stopping — Timbering — The Lake Superior iron-ore mines — 
Two methods of working them — The Kimberley diamond mines 



CONTENTS. 

— Coal mining — Laying out a coal mine — Post-and -stall method 

of getting out coal — Longwall mining — Coal cutting machinery — 

, Hauling out the coal — Various systems employed — Hoisting 

the wagons ; time-saving devices 437 

Chapter XXII.— POWER FROM FALLING WATER. 

The pressure of water — The wasted energy of Niagara Falls — Early 
attempts to use it — Great development — An industrial Niagara 
— Great installations — Facts about power companies at Niagara 
— Method of generating power — The Ontario Power Co. — Huge 
water-pipes — ^A relief weir — Types of turbines — A monster tur- 
bine — Future development of water power — High-pressure water- 
power o 467 



HOW IT IS DONE 

OR 
VICTORIES OF THE ENGINEER 



Chapter I. 
RAILROAD ENGINEERING. 

The significance of the railroad — What the railroad engineer has to 
do — Preliminary operations — The reconnaissance — ' ' Develop- 
ment ' ' — Helical tunnels — Preliminary surveys — Levelling — 
Contours — The surveyor's life — Location survey — Ranging 
curves — The theodolite — Several methods of ranging described — 
Road construction — Record tracklaying — Cuttings and embank- 
ments — Blasting rock — A trestle through a lake — Snowsheds 
— Laying the track — Preparing the ties — Standard rails — Driving 
the last spike on the Canadian Pacific Railway — Rack railways 
— Jungfrau Railway — Pike's Peak Railway. 

PKOBABLY the first kind of work that one 
thinks of in connection with the word ^^ engi- 
neering ^' is that of railroad building. That this 
should be so is due to the fact that railroad engineer- 
ing is so extremely comprehensive. For the railroad 
the biggest bridges are built; for it the longest tun- 
nels are driven through mountains and under rivers; 




for it huge gaps are blasted through the rock, and 
mighty embankments thrown across the valley. Then, 



i6 RAILROAD ENGINEERING. 

r.2:ain, the vastness of railroad enterprises grips the 
imagination. In America folk said, '" We want a 
quick waj across this continent to the Pacific/' and 
the Rockies were pierced over and over again. Rus- 
sia sighed for a port in Pacific waters, and lo ! the 
Trans-Siberian, trailing its 5,000 miles through 
steppes, swamps, forests, and mountains. To Britons 
came a vision of a steel track from Egypt to the 
Cape ; and the engineers have pushed north and south 
till the vision has almost become fact. More, they 
have throTSTi out a great branch from the Victoria 
^yanza to Mombasa on the east, and on the west 
another great feeder to Lobito Bay. In South 
America the Andes will soon be conquered by the 
Trans-Andine Railway. Before many years have 
passed trains will travel from Berlin to Bagdad; 
possibly from St. Petersburg to Calcutta. The rail- 
road men have tamed the Jungfrau and scaled Pike's 
Peak, have pushed up the Himalayas to Darjeeling, 
have taken the rails three miles into the air in Peru. 
Snow and ice do not deter them — witness the White 
Pass Railway threading storm-swept defiles once 
almost impassable to man. 

But if we attempted anything like a full list of 
wonderful railroad feats we should fill up the space 



RAILROAD ENGINEERING. 17 

allotted to this chapter. Everybody who has read 
or travelled knows well enough that the railroad engi- 
neer has no acquaintance with the word ^' can't." 
Give him the money and the men and he will make 
a road for the locomotive through anv country you 
like. 

But do you know how he does it ? Do you know 
what a tremendous amoimt of work has to be done 
before the ^' first sod " is cut, and with what care it 
must be done ? The problem before the engineer is 
by no means one of merely getting the line from one 
place to another. It includes many other consider- 
ations, which, if not allowed for, may cause much 
trouble and expense in the future. For instance, the 
engineer must decide on the most economical gradient 
to use. If made very slight it may necessitate the 
leading of the line around the country and the undue 
leng-thening of the track, with heavy upkeep expenses. 
On the other hand, an over severe gradient may reduce 
the first outlay on actual construction but be respon- 
sible for ruinous haulage costs. Curves must be kept 
as gentle as possible, to reduce friction and increase 
safe speed. The question, ^^ Shall it be a cutting or 
a tunnel ? " constantly occurs, and so do a host of - 
other questions known only to the railroad engineer. 



J 



RAILROAD ENGINEERING. 



19 



Apart from physical difficulties, there are legal 
difficulties to be overcome. In countries which are 
thickly populated, and where land is valuable, the 
lawyers play a very important part during the prelim- 
inary stages of a railway scheme. But with their 
work we will not concern ourselves — 'tis too dusty. 
Rather let us give our thoughts entirely to the engi- 
neers and track-layers, and, as the more difficult 
includes the less difficult, pay special attention to rail- 
roading in mountainous country, where its most signal 
triumphs have been won. 

PKELIMIN^AEY OPERATIONS. 

The forerunners, the scouts of the track-laying 
army, are the survey engineers and their staffs. In 
a properly worked railroad proposition not a yard of 
earth or rock is moved on any one section until the 
centre line of the track has been laid down on paper 
and transferred to the ground. The costs of the 
survey average about two per cent, of the total cost 
of construction, and the money is well spent, since 
any mistakes made in the first instance prove extremely 
expensive in the long run. 

In earlier days, before the world was as well known 
as it is now, actual exploration, attended by all the 



20 RAILROAD ENGINEERING. 

dangers and hardships that befall the explorer, had 
to precede the survey. Take the case of the Canadian 
Pacific Railway. For six years separate parties 
hunted in the Rockies and Selkirks looking for pos- 
sible paths for the rails. What they suffered may 
be read in the four hundred pages of a bulky volume 
collated by Sir Sandford Fleming, the engineer-in- 
chief. Many routes were suggested, and only after 
long and careful comparison of their relative merits 
was the final choice made. 

As a rule the railway runs, even in mountainous 
parts, through regions which have been traversed 
before, and of which more or less accurate maps exist. 
In such cases the first expedition is known as the 
reconnaissance, a trip through the country by men 
of great experience, who rapidly examine the general 
" lie of the land " and note all the details which are 
of importance. The engineer, armed w^ith an aneroid 
barometer, a compass, and an odometer (a wheel of 
known circumference drawn along the ground to reg- 
ister the distance on a dial), compares elevations, 
decides how a given rise may be obtained in so many 
miles; wdiich side of a valley will best serve; where 
precautions against sand and snow slides must be 
taken; where a tunnel is unavoidable; and so on. 



RAILROAD ENGINEERING. 



21 



In mountainoiTS passes the natural fall of the 
ground may exceed the steepest gradient permitted, 
and there will be need for '' development " — that is, 
the deliberate increase in the length of the road by 




Fig. 2.- — The upper diagram shows how the rise from a point a to another 
point B is negotiated by " developing " the line round the end of a val- 
ley. The lower diag:ram gives the relative gradients of the direct route 
(a to b) and of the circuitous route (a c d b). 

either leading it up a side valley, or making it circle 
about over itself in tunnels or in the open. Fig. 2 
shows in plan and in profile a very simple instance 
of ^' development." It is required to get from a to b. 
The direct line (dotted) has too steep a gradient to 



22 



RAILROAD ENGINEERING. 



be practicable. But by taking tlie track round the 
side of the valley^ through c and J), a comparatively 
gentle gradient is obtained. Turning to existing 
examples, we have the Marshall Pass section of the 
Denver and Rio Grande Railroad (Fig. 3), a remark- 




Fic. 3. — The Marshall Pass section of the Den\er and Rio Giamle Kailroad. 
Observe the extraordinary twists and turns whereby a moderate gradient 
is obtained. 

able feat of development. This famous pass in the 
Rockies has been subdued by a track that wriggles 
in and out along the valleys and doubles back on 
itself in such a manner as to make its length five 
times that of the direct distance from Sargent to 
Poncha. Even so it has a rise of four feet in a hun- 
dred. Some idea of the country through which it 



RAILROAD ENGINEERING. 



23 



winds to the summit level of 10,856 feet will be 
gathered from the illustration on page 22. 

Sometimes tunnels must be employed to gain 
distance in a locality where there are no side valleys. 
The Albula Eailway, Switzerland, includes three 
very remarkable helicoidal tunnels, two superimposed 




Fig. 4.- — Sketch plan of three helicoidal tunnels on the Albula Railway, 
Switzerland. The tunnels are indicated by dotted lines. 



on one another (Fig. 4). The track is led across the 
river running in the bottom of the pass no fewer 
than four times. Similar work is found on the St. 
Gothard Railway. The Darjeeling Railway, in the 
Himalayas, is also noted for its spirals. 

The engineer may have to go over the ground 
several times before he feels justified in deciding the 
general position of the line, or submitting several 
alternative routes, as on his recommendation will be 
based the succeeding surveys. 



24 



RAILROAD ENGINEERING. 



PRELIMINARY SURVEYS. 

After the reconnaissance comes the preliminary 
survey, in which instruments of precision are used — 
the level, for determining differences in height; the 
transit theodolite, for measuring horizontal angles ; 
and the chain or steel tape, for finding the distance 
between point and point. In front of the party goes 



BAC^ -SIGHT 




Fig. 5. — To show how a level is used. 



a corps of axe-men to clear away bushes, trees, and 
other obstacles which may interfere with observations. 
Then comes the transit man, recording angles and 
distances, and behind him the leveller. One method 
of using the level is shown in Fig. 5. The man in 
charge levels the tripod carefully, and turns the tel- 
escope on to a graduated pole held vertically at a 
point behind him by an assistant. The cross- wire in 
the telescope lies, say, on the 9-foot mark on the pole. 



RAILROAD ENGINEERING. 



25 



Having got his '' back-sight/' he revolves the telescope 
through half a circle, and observes a second pole set 
up a certain distance away from the first in front of 
him by assistant ISTo. 2, and finds that the cross-wire 
cuts this at four feet from the bottom. A very simple 
subtraction sum shows that the point on which the 
^^ front-sight " stands is five feet higher than that 
on which the '^ back-sight " stands. Assistant ^o. 1 
now goes forward and sets up his pole, the level is 
moved to position 2, and the process is repeated. Then 
Xo. 2 advances, and so a ^' profile " or ^^ backbone " 
line is secured gradually. 

For obtaining ^' contours " — that is, lines plotted 
on the plan to show differences in elevation on each 
side of the line — the level is set up and the ^^ flag- 
man '' moves away until the reading shows that the 
foot of his pole is the required number of feet lower 
than the level. Then the distance between pole and 
level is measured and recorded on the plan. Contour 
observations are generally made at right angles to 
the central line. 

It is often a rough life, that of the surveyor, and 
a dangerous one, too. The theodolite man working 
along the face of a gorge has at times to trust his 
life to a rope and be dangled in mid-air while he 



26 



RAILROAD EXGINEERIXG. 



records liis observations and makes his '' "bench 
marks " for future reference. Or perhaps he may 
be obliged to balance himself on logs slung from 
chains over a raging torrent, or cling cat-like to an 




Fig. 0. — The Denver and Rio Grande Railroad in the Canon of Lost 
Souls, Colorado. 
{Photo by courtesy of the Denver and Rio Grande Railroad Co.) 



ice-slope, with a freezing wind numbing his fingers 
till they can hardly operate the screws of the transit. 
But whatever be the physical conditions his observa- 
tions must be correct, as on theni depends to a great 
extent the fate of the railway. 



RAILROAD ENGINEERING. 



LOCATIOlSr SURVEY. 



27 



When the plans and profiles are all completed they 
are scrutinized at headquarters. If found unsatis- 
factory, the engineer-in-chief draws a new line or 
lines, and sends the surveying parties out again, and 
perhaps a third or fourth time. At last the word is 
given to definitely locate the track by means of pegs 
driven into the centre line or by marks made on neigh- 
boring objects. A railway is a series of straight 
portions, called tangents, connected by curves. One 
of the surveying engineer's most laborious tasks is 
to " range the curves '' in accordance with the plans. 
Its difficulty depends on the nature of the country. 
In some cases he has an uninterrupted view and can 
lay out the curve without ' shifting his instruments; 
in others — as for instance when he has to round the 
shoulder of a mountain — the curve must be picked 
out piecemeal, by working from point to point and 
constantly referring back. 

THE EANGITs^G OF CURVES. 

The instrument used for this purpose is the transit 
theodolite (Fig. 7), which measures angles both ver- 
tically and horizontally. It is a telescope mounted 



28 



RAILROAD ENGINEERING. 



on standards resting 
on a circular disc 
which revolves on a 
table attached to the 
top of a tripod. The 
base is levelled by 
means of three or 
fonr screws between 
the tripod top and 
the table. 

The telescope can 
be turned over ver- 
tically — transited — 
between the stand- 
ards, and the stand- 
ards revolved with 
the horizontal disc. 
Attached to the tele- 
scope is a circular scale, marked to degrees and frac- 
tions of a degree for comparison with a fixed vernier 
projecting from the standards. The base is similarly 
graduated. The user is thus enabled to measure 
angles both vertical and horizontal. 

Curves are set out to a given radius by one or 
other of several methods. We may begin with the 




Fig. 7. — A transit theodolite. (Messrs. 
Stanley and Co., Ltd.) 



RAILROAD ENGINEERING. 



29 



usual American practice, which is illustrated in Fig. 
8. The theodolite is set up at a and sighted back 
along the straight piece of track or tangent from 
which the curve springs. It is then transited — - 
turned head over heels — to point towards a point x. 
If the curve is to be one of '^ 48 degrees/' the observer 
now revolves the telescope inwards horizontally 




^^ Fig. 8. — Ranging curves (American method). 

through half that number of degrees till it lies on 
the line a b^ and a spot b is marked on the line 
exactly 100 feet from a. The diagram explains what 
is meant by a curve of any particular number of 
degrees — namely, a curve in which an arc standing 
on a chord 100 feet long subtends an angle of that 
number of degrees at the centre of the circle of which 
the curve is part. The centre may be in the heart 



30 RAILROAD ENGINEERING. 

of a mountain, but that makes no difference ; the engi- 
neer knows that if he lays the angles out correctly 
the curve will be all right. 

Having established his first point, b^ he moves his 
theodolite thither, and sights it along bx, making an 
angle of 24 degrees with ba. This line bx is the 
new tangent. The instrument is transited to point 
towards y^ and the angle ybc turned off, and c is 
established 100 feet from b ; d and other succeeding 
points are found in the same way until the curve is 
complete. 

In actual practice curves are seldom sharper than 
10°. The engineer has tables to show him what 
number of degrees represent a curve of a certain 
radius. Thus, if he wished to lay out a curve on a 
2,865-foot radius he would turn up his tables and 
find that this is a 2° curve, and that the angle bax 
would be one of 1°. A 10° curve has a radius of 
573.7 feet. 

In some cases it is possible to sight every point 
without moving the theodolite (Fig. 9). The engi- 
neer sights along the tangent abc^ and turns off an 
angle cbd^ half the number of degrees of the curve, 
as in the first case; and his assistant places a peg 
at D^ 100 feet from b. He then turns off angle 



RAILROAD ENGINEERING. 



31 



DBE^DBC^ and the 100-foot chain is carried round on 
D as a pivot till the free end encounters line b. e. This 
gives him the second point, e. So in succession angles 




"FxG. 9. — Ranging curves from fixed point, by equal angles. 

EBF^ FBG, GBH^ are turned off (all equal to dec) and 
points F^ G^ H^ established. The position of the next 
point, 1, is not visible from b^ because an obstruction, 
o^ intervenes. Therefore the theodolite is moved to y, 




Fig. 10. — Ranging curves on marshy ground. Two theodolites used. 



Sighted on h^ and turned off through the proper 
angle. 



32 



RAILROAD ENGINEERING. 



On marshy ground (Fig. 10), where the use of a 
chain may be impossible, two theodolites are set up 
on the track tangents to be connected, and a man is 
sent to stake out the points a^ b^ c on which the two 
lines of sight meet when the instruments make certain 
angles with a base line connecting them. 

Ranging by ''offsets '' (Fig. 11) can be done with- 
out a theodolite. The tangent is produced along ab 
for 100 feet, and the measuring chain carried round 




on A into line a c^ c being a certain distance from b. 
Then ac is produced 100 feet to d^ and f found by 
carrying round the chain to e, de being twice bc. 
The point g is found by producing ce to f, and off- 
setting to G, making fg = de. The degree of curva- 
ture depends on the length of the offsets, de^ fg^ etc., 
which are deduced from tables. As a matter of fact, 
the angle dce or feg contains the same number of 
degrees as ce or eg would subtend at the centre of 



RAILROAD ENGINEERING. 



33 



the circle. Hence all four methods arrive at the same 
results. 

Some curves are not regular, but increase or 
decrease in sharpness from one end to the other. 
These are known as transition curves, and are ranged 
in a manner with which I need not trouble you. 
Then, again, we have compound curves, bending right 
or left as well as rising or falling. In mountainous 
regions most of the curves are of this character. 

ROAD CONSTRUCTION. 

When the location survey is finished, the con- 
struction engineer takes command. The line is 
divided into sections, and each section let to a con- 
tractor, working under the supervision of an engi- 
neer. The chief contractors probably sublet the 
brid2:e-buildino: and tunnel-drivinff that mav be neces- 
sary to specialists in these branches of construction. 

The maintenance of an army of men in outlying 
places is in itself no small task. Huts must be built, 
and provisions supplied for man and beast, and stores 
of all kinds and machinery be collected and moved 
from place to place as the work proceeds. 

On a big line operations start at as many points 
as conditions permit. Where the track will run 

3 



34 



RAILROAD ENGINEERING. 



through uninhabited country, the rail has to feed 
itself, and can therefore be pushed out from the ends 
only. During the building of the Canadian Pacific 
Railway one army drove westwards across the prairie 
and the Rockies, while another toiled painfully east- 




PlG. 12. 



-Eagle River Canon, Colorado, showing new double tracking, one 
track on each side of the river. 



wards from the Pacific coast to meet the first. All 
supplies had to be taken over the rails already laid. 

In open prairie country where there are practically 
no gradients, and there is a good soil, work proceeds 
at a great pace, the road-bed being thrown up from 



RAILROAD ENGINEERING. 



35 



ditches on both sides either by hand or by special 
machines. The ^' Canadian Pacific " builders made 
a tracklaying record of 6^ miles in one day. In 
twentj^-fonr hours 16,000 ties or sleepers were placed, 
and 2,120 lengths of rail fixed to them with 63,000 




Fig. 13. — A steam-shovel at work in a cutting. 

spokes. In the Cape to Cairo route eight miles have 
been laid in a day ! 

The normal rate of progress even in open country 
is much less sensational, and where big cuts and fills, 
tunnels and bridges, occur one after the other becomes 
very slow indeed. In moving " dirt " in cuttings the 
contractor is greatly assisted by the '^ steam shovel/' 



36 



RAILROAD ENGINEERING. 



a huge ladle mounted on the end of a beam, which 
scrapes three tons or more of stuff from the bank 
each stroke, and drops it into wagons. It will dig 
as much in a day as some hundreds of men. Fig. 13 
is a picture of one of these shovels at work. 



"m^m» 





Fig. 14. — A rough contractor's 



road " beside a finished track. 



The dirt from the cuts is run away over rough 
^' contractors' tracks " (Fig. 14) and either dumped 
on a spoil bank, or used to make an embankment. 
The engineer is careful to balance the cuts and fills 
as evenly as possible, so that there may be little waste 
of labor. An embankment is formed either by 



RAILROAD ENGINEERING. 



37 



making it build itself, as it were, the rails being 
extended along it and the wagons tipped over the 
gradually advancing end (Fig. 15) ; or stagings are 
constructed across the depression and the fill is made 
from the centre outwards, the staging being gradually 
removed as the bank increases. 




Pig. 15. — ^Forming an embankment by end-tipping. The " tip-heads " are 

separated by " gullets " (depressions), to be filled by side- tip wagons. 

The steepness of the sides of a cutting depends on 
the nature of the material. Through rock and chalk 
they may be perpendicular, but where sand and clay 
occur the inclination of the slope to the horizontal 
must be the '' angle of repose " of the substance. Wet 



38 



RAILROAD ENGINEERING. 



clay is tlie most troublesome material, as it will not 
stand a steeper slope than 16 degrees. ISText to it 
comes sand. The drainage of the sides of a cutting 
is effected by digging deep trenches and filling them 
with chalk, stones, or other stuff (Fig. 16), through 




Pig. 16. — Draining the side of a cutting by trenches filled with chalk. 
(Photo, Great Western Railway Co.) 

which the water can easily find its way to drains laid 
at the foot of the slopes (Fig. 17). The amount of 
earth moved in the building of . some lines is enor- 
mous. On the South Western Railway, between 
London and Southampton, it was calculated that the 



RAILROAD ENGINEERING. 39 

aggregate earthworks represented a mass sufficient to 
form a pyramid having a base of 150,000 square 




Pig. 17. — Section of a cutting, showing drains, ballast, ties, and rails. 

yards and a height of 1,000 feet; and even these 
figures have been exceeded elsewhere. 

BLASTING THE ROCK. 

Earth work is, however, very easy compared with 
the blasting of a ledge along the face of a rocky gorge, 
such as that at Lengue on the Benguela Railway in 
Portuguese South-West Africa. In order to keep 
well above the level of the watercourse it was decided 
to carry the line along the cliff at the side of the 
gorge. The rock was so hard that it could be removed 
by blasting only. Here is a little pen-picture of the 
operations as given in The World's Worh: ^' Work 
was carried on night and day. An electric lighting 
plant was brought up from the coast and installed 
at the railhead, while across the gorge cables were 
stretched from which lamps were suspended. In the 




I 



Fig. 19. — The same : after the explosion. 
{Photos, Great Western Railway Co.) 



RAILROAD ENGINEERING. 41 

fitful gleams of the blue light thrown by the electric 
arc lamps the natives worked away in the dead of 
night with the rock-drills, boring holes for the inser- 
tion of the dynamite blasting cartridges When 

the holes were driven right into the rock-face and 
the cartridges had been tamped home, the electric 
lights were hauled along the cables to a safe distance 
from the force of the concussion, while the natives 
also retired out of danger's way. In the stillness 
of the night there would suddenly be heard the dull, 
muffled roar of the blasting charges, growing in 
intensity as the rock disintegrated, and amid a cloud 
of heavy smoke, dust, and debris a gaping hole was 
torn into the side of the rock cliff .... Immediately 
after the explosion had died away the natives scam- 
pered to the rock-face once more and set to work with 
their drills as if their lives depended upon it, while 
other gangs began vigorously clearing away the 
masses of rock disintegrated by the previous explosion, 
and levelling down the ground ready for the rails, 
which w^ere laid as quickly as possible. Day and 
night this went on, with the gangs working in shifts, 
until after a few weeks the top of the gorge was 
reached. In excavating this section of the line sev- 
eral million tons of rock were moved. . . .Throughout 



42 



RAILROAD ENGINEERING. 



this stretch the line is flanked on one side bj a per- 
pendicular wall of granite rising sheer for several 
hundred feet. On the other 
side there is a corresponding 
drop into the valley below." 

Tnnnel making and bridge 
building are treated in other 
chapters, so, although they oc- 
casion some of the most diffi- 
pf cult work in railway construc- 
tion, they need not be described 
here in detail. We may spare 
a word, however, for the won- 
derful trestles that are thrown 
across deep valleys and swamps, 

ledge. The dotted line shows SOmC risiug huudrcds of fcct 
the original extent of the 

rock. into the air, and apparently far 

too frail for the load they have to carry; some sweep- 
ing in wide curves. An immense amount of timber 
is used in these bridges, but there is a general tendency 
nowadays to substitute steel for such inflammable 
material. 

Occasionally the engineer experiences great trouble 
in securing a firm foothold for the trestle-feet. A 
notable case is that on the " Lucin cut-off " which 




Pig. 20. — Track 



a rock 




Fig. '21. — The building of a biitk iail\\a\ budge, showing the .wooden 

" centres " or supports for the arches during construction. 

{Photo, Great Western Railway Co.) 




Fig. 22. — Steel " centres " used in building arches of bridge at Mount Union, 

Pennsylvania Railroad. 

{Photo, Pennsylvania Railroad Co.) 



44 RAILROAD ENGINEERING. 

the Southern Pacific Eailway has pushed across one 
end of Great Salt Lake, Utah. In the deeper water 
long piles to carry the track were driven into what 
appeared to be hard solid ground, but afterwards 
proved to be only a crust of salt and sand on the top 
of a soft substratum of great depth. The piles sank 
in and the trestles collapsed. Then the engineers 
tried to make a solid embankment of rock; but the 
material was swallowed up without effect, though 
some thousands of tons were emptied daily for several 
weeks. Finally, it was decided to base the trestles 
on timber cribs filled with stone and sunk to the 
bottom of the lake. The laying of ten miles of cribs 
through deep water has been a task that exceeds even 
the fiUing-in of Chat Moss, between Liverpool and 
Manchester, by the redoubtable George Stephenson. 

SNOWSHEDS. 

Where the railway rises above the snowline and 
skirts slopes down which avalanches may rush at 
certain seasons, it is necessary to protect the track by 
miles of snowsheds. These are constructed of very 
stout timbers, and either anchored to the hill-side 
so that the roof forms a continuation of the slope, 
as in Figs. 23, 2-i, and 25 ; or made of ^' double 



RAILROAD ENGINEERING. 



45 



span " shape (Fig. 26) where they have to withstand 
a vertical fall. Weight is given to the structure by 




Fig. 23. — Snowshed. 



attaching it to cribs filled with rock. The woodwork 
being very inflammable, and the shape of a tunnel 
such as to assist the spread of flames, it is necessary 




Fig. 24. — Snowshed : another type. 



to install fire-extinguishing apparatus and establish 
fire pickets. Also, as a further precaution, the shed 



46 



RAILROAD ENGINEERING. 



is broken into short lengths by ^' fire-breaks," to 
isolate a conflas^ration. At a fire-break the snow is 




Fig. 25. — Snowshed: another type. 

deflected from the uncovered track by V-shaped cribs 
with the apex pointing np-hill (Fig. 27). On the 
Southern Pacific Railroad the snowsheds contain tel- 
escopic portions, which are closed during the stormy 




Fig. 26. — Vertical-fall snowshed. 



season, but opened in summer or in event of a fire. 
The movable lengths, about fifty feet long, run on 



RAILROAD ENGINEERING. 



47 



wheels on a wide-gauge track laid outside tlie main 
track. They are easily moved in or out of the larger 
fixed parts of the shed by a locomotive or man-worked 
tackle, and have successfully stopped what might have 
proved very serious outbreaks of fire. The longest 
stretch of. snowshed is on the Central Pacific Kail- 







Fig. 27. — V-shaped crib to deflect snow from an opening in a snowshed. 

road, where it crosses the Sierra Nevada. For thirty- 
three miles the track is continuously protected. Three 
^' fire trains " are always ready, with steam up, to 
carry the fire brigade at a moment's notice to any 
threatened spot, when the watchmen, who are 
on duty night and day, telephone the necessary infor- 
mation. 



48 



RAILROAD ENGINEERING. 




Fig. 28. — Snowshed on Canadian Pacific Railway. 
(Photo, Wm. Notman and Son, Montreal.) 



LAYING THE TRACK. 

When the road bed has been graded, it is covered 
to a depth of about a foot, and for an average width 



RAILROAD ENGINEERING. 



49 



of 10 feet, with '' ballast " — that is, gravel, or stone 
broken up till it will pass through a 2-inch ring. 
This is drawn on by carts, and spread very carefully 
to the required surface, and affords a firm and well- 




FiG. 29. — Cutting and embankment. 

drained foundation for the sleepers or ties. These 
last are usually of pine, treated with creosote or some 
other preservative. Creosoting, the most commonly 
used process, is done as follows: The ties are piled 
on iron carriages and run into a long iron cylinder, 
4 



50 RAILROAD ENGINEERING. 

the ends of wliicli are then fastened on and made 
air-tight. For several hours the space inside is 
alternately exhausted of its air by a vacuum pump 
and filled with steam, to extract the air and water 
from the pores of the wood. Finally all the air is 
drawn out, hot creosote oil injected, and air-pumps 
set to work to create an air-pressure of 100 lbs. to 
the square inch. This forces the creosote into the 
pores of the wood. At the end of a couple of hours 




J I Tie i I Fig. 31. — Bull -headed rail in 

I {^vv,.^ ^.-^\ \ " chair." k is the wooden key 

I ' ^-Spikw--^ ■' '• to hold rail tight. 

Fig. 30. — Standard rail section. 

or so the oil is drawn off, the cylinder covers are 
removed, and the ties are pulled out ready for laying 
and spacing. 

The standard section of the ^^ flat-footed '^ rail used 
in the United States and most other countries is 
shown in Fig. 30. The rail is attached to the tie by 
a pair of spikes, driven out of line with one another, 
the heads overlapping the lower flange. In the 
British Isles and in some Continental countries the 
'^ bull-headed " rail (Fig. 31) is employed. Heavy 



RAILROAD ENGINEERING. 51 

cast-iron ^' chairs " are bolted to the ties before they 
are laid, and in these the rail rests, wood blocks (k) 
driven in between its outer side and the chairs hold- 
ing it firmly in position. This system of rail laying 
makes the replacement of rails a very easy matter, 
and it is free from the trouble of loose spikes. But 
it is more expensive in the first instance, and so does 
not find favor on lines where economy is of first 
importance. 

At curves the outer of a pair of rails is " super- 
elevated " to give the train a tilt inwards and counter- 
balance the centrifugal force which, were both the 
rails on a level, would tend to throw the wheels off 
the track. The superelevation is proportioned to the 
speed at which the trains will be permitted to take 
the curve. On express routes, where the tilting is 
considerable, it may be felt distinctly by the traveller. 
Many accidents have been due to drivers exceeding 
the speed limit for which allowances were made by 
the track layers. 

THE LAST SPIKE. 

The cutting of the first sod of a railway is often a 
great ceremony. Bands play; and a procession is 
formed and marched to the spot where the function 



:* 



52 

!?^^C!' ^ ^ 111 



RAILROAD ENGINEERING. 




Fig. 32. — Royal Gorge, Grand Canon, the Arkansas, Colorado. This is the 
deepest chasm in the world through which a railroad passes. The walls 
rise 2,627 feet above the track. In the background are seen the girders 
supporting a hanging bridge. 

(Photo, Denver and Rio Grande Railroad Co.) 

is to take place. The chairman makes a speech and 
the engineer-in-chief hands him a silver-bladed spade, 



RAILROAD ENGINEERING. 53 

with which he digs out a sod and transfers it to a 
barrow of elegant design. Everybody cheers, and 
then there is a general move to the tent or building 
where a great banquet has been prepared. 

Years pass, and the day arrives when the last 
spike is to be driven. Though this marks the com- 
pletion of a great work, it is often accompanied by 
very little of the shouting that was heard when every- 
thing remained to be done. In many cases this is 
only natural, as the rails started from a thickly pop- 
ulated spot, and the last spike may be driven in the 
midst of a wilderness. Yet the closing scene is really 
far the more dramatic. 

Sir Sandford Fleming has described in eloquent 
words the last episode in the building of the 
Canadian Pacific Railway., They are well worthy of 
quotation. 

"Early on the 7th [of I^ovember, 1885] the 
junction was verging to completion, and at 9 o'clock 
the last rail was laid in place. All that remained 
to finish the work was to drive home one spike. By 
common consent, the duty of performing the task was 
assigned to one of the four directors present, the 
senior in years and influence, whose high character 
placed him in prominence — Sir Donald Alexander 




o 5 

^ -a 

= 2 



^1 



'W^ 


f 

t-l 

O 
a 
*3 
a 
§ 
1 


^? 


' V 


1 

CO 

CO 
fa 



RAILROAD ENGINEERING. 55 

Smith. !N^o one could on siicli an occasion more 
worthily represent the Company or more appropri- 
ately give the finishing blows, which, in a national 
cause, were to complete the gigantic undertaking. 

" Sir Donald Smith braced himself to the task, 
and he wielded the by no means light spike hammer 
with as good a will as a professional tracklayer. The 
work was carried on in silence. !^othing was heard 
but the reverberation of the blows struck by him. 
It was no ordinary occasion; the scene was in every 
respect noteworthy, from the group which composed 
it and the circumstances which had brought together 
so many human beings in the heart of the mountain, 
until recently an untracked solitude. Most of the 
engineers, with hundreds of workmen of all nation- 
alities, who had been engaged in the task, were 
present. Every one appeared to be deeply impressed 
by what was taking place. . . .AH present were more 
or less affected by the formality which was the cro^vn- 
ing effort of years of labor, intermingled with 
doubts and fears and oft-renewed energy to overcome 
what at times appeared unsur mount able. To what 
an extent the thoughts of those present were turned 
to the past must, with that undemonstrative group, 
remain a secret with each individual person. . . .The 




B S 






O 4J 



3 

p. EC 

S CO 

9 .o 



a .. 



RAILROAD ENGINEERING. 



57 



blows on the spike were repeated until it was driven 
home. The silence, however, continued unbroken, 
and it must be said that a more solemn ceremony had 
been witnessed w^ith less solemnity. It seemed as if 
the act now performed had worked a spell on all 
present. The abstraction of mind, or silent emotion, 
or whatever it might be, was, however, of short dura- 
tion. Suddenly a cheer spontaneously burst forth, 
and it was no ordinary cheer. The subdued enthu- 
siasm, the pent-up feelings of men familiar with hard 
work, now found vent. Cheer upon cheer followed, 
as if it was difficult to satisfy the spirit which had 
been aroused. Such a scene is conceivable on the 
field of hard-fought battle at the moment when victory 
is assured. 

" Not unfrequently some matter-of-fact remark 
forms the termination of the display of great emotion. 
As the shouts subsided, and the exchanges of congrat- 
ulations were being given, a voice was heard in the 
most prosaic tones, as of constant daily occurrence: 
^ All aboard for the Pacific' The notice was quickly 
acted upon, and in a few minutes the train was 
in motion. It passed over the newly laid rail, 
and amid renewed cheers sped on its way west- 
ward." 



58 



RAILROAD ENGINEERING. 




Fig. 35. — Low-pressure cylinders of 286J-ton locomotive. 
(Photo, American Loco. Co.) 



RACK RAILWAYS. 

When the gradient exceeds 4 feet in 100 it is 
economical^ and may be necessary, to make a rack 
railway. The rack is laid between the ordinary 
smooth rails, and engages with the teeth of a large 
cog driven by the mechanism of the locomotive. 
Switzerland contains the majority of the well-known 
rack railways — the Pilatus, Rigi, Wengeralp, Zermatt, 
Rothhorn, Jungfran among them — but most moun- 
tainous tourist resorts in other countries can boast 



RAILROAD ENGINEERING. 59 

one or more examples. Of the Swiss the Jimgfrau 
is the most extraordinary. It starts at Kleine 
Scheidegg, 6,710 feet above sea level and climbs up 
in the open to Eigergletcher (7,560 feet). Then it 
plunges into a succession of tunnels, between which 
the traveller gets glimpses of splendid prospects, and 
w4nds slowly up past Eothstock, Eigerwand, Eismeer, 
and Jungfraujoch stations — cut in the solid rock — 
to a point 216 feet below the summit of the mountain, 
which is 13,886 feet above sea-level. A lift, operated 
by electricity, as is the railway itself, transfers passen- 
gers to the actual summit, which commands a splendid 
view of the whole Alpine region of Switzerland. 

The railway is for the most part a tunnel through 
limestone and gneiss. It took nearly ^yq years to 
survey the course, owing to the extreme diihculty of 
finding stations for the instruments, though it is only 
a few miles long. But by way of compensation the 
construction could be continued in winter as well as 
summer, as the workmen in the timnels were pro- 
tected from the cold outside. Also the proximity of 
the tunnels to the face of the cliff made it easy to 
get rid of the rubbish by driving short cross tunnels 
to the face at intervals, and dumping it down the 
mountain-side. 



6o RAILROAD ENGINEERING. 

The track has a gauge of 3% feet (one metre). 
The engine will move a train and eighty passengers 
np the steepest grade (1 in 4) at an average speed 
of about 5 miles an hour. To control the descent 
there are three separate brakes, each capable of stop- 
ping the train by itself. And so any one can easily 
ascend and safely descend the peak which once was 
accessible only to the daring mountaineer. 

PIKERS PEAK RAILWAY. 

More than a hundred years ago Lieutenant Zebulon 
W. Pike, in command of a squad of private soldiers, 
guides, and Indians, was exploring the Rockies when 
he sighted in the distance a " great white peak," 
which appeared to him quite inaccessible to man. 
Eighty-five years later there was completed a cog rail- 
way running from Manitou Station, on the Denver 
and Rio Grande, to the summit of the peak named 
after the bold explorer. Manitou is 6,000 feet above 
the sea; the Peak lies 8,108 feet higher, and the rise 
is managed by a track rather less than 9 miles long, 
having an average gradient of 19 feet in 100. The 
road-bed is solid and from 15 to 20 feet wide, 
leaving fully 5 feet on each side of the cars. At 
intervals of 200 feet the track is anchored to solid 
masonry to prevent any possibility of its sliding on 




RAILROAD ENGINEERING. 



6i 



its bed. Every locomotive has three cog and pinion 
appliances, which can be worked together or inde- 
pendently. In each cog is a double set of pinion 
brakes, either one of which can stop the engine in 
ten inches, up hill or down, on the steepest gradient 




Fig. 36. 



-Pike's Peak Mountain Railway in the winter. 
{Photo, "Cassier's Magazine.") 



and when travelling at the maximum speed allowed. 
The car, which is not coupled to the locomotive — 
always at the down-hill end, so as to reduce the danger 
of derailment — is itself furnished with separate 
brakes. Even during the tourist season snow-ploughs 
have to be used frequently to keep the track open. 



62 RAILROAD ENGINEERING. 

This loftiest of rack railways gives the sightseer 
the most glorious views, and at the same time im- 
presses him bv the wonderful character of the engi- 
neering that made it. ^o physical obstacle was 
sufficiently formidable to check the upward progress 
of the track. It skirts giddy precipices, down which 
one looks shuddering but safe, and finishes with a 
straight climb on a gradient of 25 in 100 to the 
Peak, where the tourist may ramble and feast his 
eyes to the full. 

Yet this railway does not climb so far skywards 
as one in Peru worked by ordinary adhesion loco- 
motives. The Callao-Oroya line, built in the seven- 
ties by Henry Meiggs, the famous contractor, rises 
15,665 feet in its 140-mile course through the Andes. 
For 100 miles the track climbs continuously, winding 
and zigzagging in a most extraordinary manner, cross- 
ing streams on dizzy bridges, burrowing through the 
rocks, creeping along tremendous precipices. At one 
place it was necessary to make a reversing switch in 
a tunnel — a imique feature. The railway is one of 
the most extraordinary feats of engineering ever 
accomplished by man, and I regret that lack of space 
forbids a fuller description." 

* The reader will find further information about this road in "The 
Romance of Modern Engineering." — A. W. 



Chapter 11. 

A RAILWAY THROUGH THE SEA:— 
TRAIN FERRIES. 

The Florida Keys — A great project — Difficult surveying — Labor 
troubles — Embankments made by dredges — ^Vast quantities of 
materials transported by sea — A railway of ^daducts — ^Work at 
Key West — A train ferry to Havana — Other train ferries — Sea 
ferries — How a train is embarked and landed — Danish ferries — 
Ferries on the Great Lakes — The Baikal. 

IF yon consult a good-sized map of Florida and 
the Gnlf of Mexico, yon will notice a chain of 
small islands stretching out like a long tail in a 
south-westerly curve towards Cuba from the south- 
east corner of the peninsula. These islands, mostly 
coral reefs covered with swamps, and kno^vn as the 
Florida Keys, have until recently been of little value 
to the United States, wdth the exception of Key West, 
the most southerly, which rose into prominence as a 
naval station during the Spanish-American war of 
1898. From Key West to Havana, in Cuba, is a 
distance of 90 miles or so, only a few hours' voyage. 
]^ow, the United States have great interests in Cuba, 



64 A RAILWAY THROUGH THE SEA. 

and for this reason Key West has become the ter- 
minus of a railway connected with the systems of the 
mainland. ^^ A railway ? '' you may ask. ^^ But 
Key West is separated by many leagues of sea from 
Florida ! '' Yes, but the Keys string out in line 
across the bay for two-thirds of the distance, and the 
water between them is comparatively shallow, and so, 
through the enterprise of one man, Mr. Henry M. 
Flagler, owner of railways and hotels galore on the 
east coast of Florida, the engineers bridged island to 
island imtil they made a secure way for the loco- 
motive from lliami to Key West — 130 miles of some 
of the most extraordinary railway work ever accom- 
plished. This really is a railway through the sea, 
for at places the traveller, looking from the car 
window, has nothing between him and the horizon 
but the waters of the Gulf and the Atlantic Ocean. 

The undertaking was accompanied by immense 
difficulties. The surveyors who went out to seek a 
path through the Everglades, the almost impassable 
morasses and wilderness that cover the southern part 
of the peninsula, to Cape Sable, suffered as few sur- 
veyors have suffered; and the making of observations 
among the Keys was anything but a picnic, since 
much of the work had to be done afloat, amid the 



A RAILWAY THROUGH THE SEA. 65 

foul exhalations of mangrove forests and clouds of 
thirsty mosquitoes. Some of the Keys are so low 
and so far apart that towers had to be built on them 
to raise the theodolites to a sufficient height to view 
land across the straits. 

The actual construction was handicapped by the 
refusal of the better class of railroad men to take 
part in a scheme that necessitated their living largely 
on houseboats^ among the most dismal surroundings. 
The hands that were collected by the energetic gen- 
eral manager, Mr. Joseph K. Parrott, proved tough, 
and in many cases useless, customers, who would 
have been unmanageable had not the authorities rig- 
orously suppressed the sale of alcoholic liquors. Yet 
many of them were brave fellows, otherwise the 
enterprise would not have reached completion. 

Starting from Miami, on the mainland, the track 
was pushed for thirty miles through the outskirts of 
the Everglades to the Keys. On this portion of the 
work powerful dredges were set to excavate two par- 
allel canals and pile up the mud into an embankment 
between them. On the top of this the first stretch 
of rails was laid. When the Keys were reached, the 
coral and limestone of which they consist had to be 
blasted and heaped. It was possible to span the 

5 



66 



A RAILWAY THROUGH THE SEA. 




smaller sea gaps and the lagoons with mud embank- 
ments accumulated by very shallow-draught dredges 
of special construction, but the larger gaps required 
trestle-work and the building of long arched viaducts 

of reinforced concrete, 
fringed with walls to 
protect trains from 
the wdnd and Avater 
when a hurricane 
swoops down on the 
Gulf. One gap is 
four miles, another 
two miles, and a third, 
from Knight's Key 
to Bahia Hondo, 
seven miles across. 
The last of these is 
bridged in part by a 
viaduct of 120 arches, 
resting on twenty- 
eight piles each, capped with a 9-foot layer of con- 
crete. Of cement 300,000 barrels, of rock 200,000 
cubic yards, of timber 3,000,000 feet, and of steel re- 
inforcing rods 7,000 tons have been consumed in this 
one link, and large as the figures appear they repre- 




FiG. 37. — Sketch map to show the track 
of the Florida East Coast Railway Ex- 
tension across the Florida Keys. 



A RAILWAY THROUGH THE SEA. 67 

sent but a small part of the total material required 
for the railway, all of which was brought to the scene 
of operations on shipboard. The mere transporta- 
tion of such bulk employed a large fleet of vessels, 
and hundreds of flat-bottomed boats to land the stuff 
through the shallow waters surrounding the islands. 
Hardly less formidable was the task of feeding and 
housing several thousands of workmen in a region 
remote from any large base of supplies. 

The railway is practically a series of viaducts and 
embankments. Thirty miles of open sea are traversed ; 
thirty miles of swamp and lagoon. Several storms 
have scattered the working force from time to time, 
tind taken their toll of human life, but the waves 
liave made no impression on the great barrier that 
now checks their career. 

To make a fit terminus for the railroad at Key 
West long walls have been built near the sea-front 
and huge quantities of mud lifted over them by 
suction dredges from the sea-bottom. Thus at one 
operation is obtained a large area of reclaimed land 
and a deep-water roadstead for shipping. From Key 
West great steam ferries transport trains bodily to 
Havana. It is thus possible to travel, without 
changing cars, from ^ew York to Havana in forty- 



68 A RAILWAY THROUGH THE SEA. 

eight hours. From Havana to Santiago, on the 
south-east coast of the island, is a run of another 
twenty-four hours; and thence to the Isthmus of 
Panama, a fifty-hour voyage. So this strange rail- 
way brings I^ew York within six days of the Panama 
Canal, a fact that in itself is of the greatest impor- 
tance, apart from the revival of prosperity in Cuba 
which such easy communication must eventually lead 
to. And all this has happened because one man 
put down $15,000,000 and said, ^^ E'o matter what 
the difficulties may be, I want a railroad made across 
those coral reefs." And his behest has been obeyed 
with a speed that reflects the highest credit on all 
concerned, for the Florida East Coast Railway Ex- 
tension was begun only in 1905. 

OTHEK TRAIN FEERIES. 

A short review of the world's chief train-ferry 
systems will no doubt interest the reader. The 
majority of these form part and parcel of the great 
American lines which link up districts separated by 
large sheets of water. To take the Sea Ferries first. 

The ]!^ew York, Philadelphia, and Norfolk Rich- 
mond Co. operates a train ferry from Cape Cha,rles 
to Norfolk, across Chesapeake Bay, a distance of 36 



A RAILWAY THROUGH THE SEA. 69 

miles. The ferry line includes a number of flat 
cargo barges, some fitted with three rail tracks, the 
rest with four tracks. These floats are towed to and 
fro by tug boats, over waters that are often as rough 
as those of the open sea. ^^ Upon arriving at the 
terminals, the barges are secured to bridges, which are 
carried on water-tight pontoons, rising and falling 
with the tide. These bridges are fitted with four 
toggle bars which engage in four toggle eyes on the 
end of the barges, for the double purpose of centering 
the barge with the bridge, so that the rail ends on 
each may fit together, and of maintaining its height. 
The barges are held to the bridges by steel mooring 
cables, attached to large mooring eyes on the decks, 
and drawn taut by winding machinery on the bridges. 
. . . .The cars are drawn off by a locomotive.'' 

The utility of this ferry may be gathered from the 
fact that it transports over 60,000 cars and 700,000 
tons of freight every year. 

^ew York Bay is the scene of the operations of 
four ferry lines, handling millions of tons of freight 
annually. The longest trip is one of 8% miles, from 
Long Island to Greenville Station. 

On San Francisco Bay we find the Solano, one of 
the largest ferry steamers in existence, at work. With 



70 A RAILWAY THROUGH THE SEA. 

a length of 424 feet and a beam of 64 feet, she is 
able to accommodate on her 4 rail tracks 27 passenger 
or 42 freight cars. 

In Enropean waters a steam ferry forms links in 
the railway service between Berlin and Copenhagen. 
Arriving at Warnemlinde, on the Prnssian coast, the 
train is transferred on to a steamer which carries it 
to Gjedser, on the island of Falster, 26 miles away. 
A short land journey follows to Orehoved, at the 
north of the island, where the^ train goes to sea once 
more. It lands at Masnedoe, and then has a clear 
overland run to the Danish capital. Copenhagen has 
train-ferry connection with Malmoe in Sweden ; and 
there are five other ferries linking up the various 
parts of Denmark. 

LAKE FEKEIES. 

A map (Fig. 38) sIioavs the routes and lengths of 
the several ferry systems on Lake Michigan, which 
has a breadth of 84 miles and a length of 345 miles. 
The strong gales which at times vex this large sheet 
of water raise waves 20 to 25 feet high, and in winter 
fogs and ice render navigation difficult and dangerous. 
Yet the great ferry steamers and train barges ply to 
and fro, the steamers being built to cut through ice 




CHICftQO 



MAP OF LAKE MICHIGAN 

SHOWING TRAIN FERRY L,INES 

IN OPERATION. 



Fig. 38. — Map of train ferry routes on Lake Michigan. 
{By permission of E. de Bodakowski, Esq.) 



72 A RAILWAY THROUGH THE SEA. 

4 feet thick. The efficiency of these ice-breaking 
steamers led the Russian Government to build the 
Baikal train ferry, which for some years transported 
the trains of the Trans-Siberian Railway across the 
lake after which it was named. The Baikal is a vessel 
of 4,000 tons, built up of pieces that had to be trans- 
ported by sea, rail, and river from ]N'ewcastle-on-Tyne 
to the lake, where they were assembled under the eye 
of English engineers. 



Chapter III. 
THE BUILDING OF A BIG SHIP. 

The ocean liner — Shipbuilding — Two mammoth vessels — Planning a 
ship — Sheer draught — Detail drawings — Experimental model — 
The building sheds — The structure of a ship — Keel, frames, 
floors, and other details — The skin of a ship — Shipwrights at 
work — Assembling the framework — The plating — Riveting — 
Preparations for the launch — Moving and standing ways — 
Greasing the ways — The drags — The launch — The engines of the 
big ship — Huge turbines — Fitting out the ship — ^The official 
trials — Ruskin on ships. 

THERE are few, if any, more magnificent sights 
than a huge steamship cleaving her way 
full speed ahead through the open sea or coming 
majestically to her berth at the pier side. Her 
towering funnels, her huge hull, contrasting in size 
so strongly with the pigmy passengers and crew, make 
one wonder how puny man can fashion such an enor- 
mous ark to carry thousands of his -kind across the 
raging waters of the ocean, for but few of us have 
ever seen a " liner '' in the making. 

Now, shipbuilding is a very complicated business, 



74 THE BUILDING OF A BIG SHIP. 

founded upon many mathematical formulae formid- 
able enough to frighten a seeker after knowledge if 
he happen to pick up a technical book on the subject. 
Even the practical work of piecing together the 
thousands of parts that go to the making of a ship 
requires very skilled labor, and very careful labor, 
too, since nothing but the best is good enough for the 
leviathan which will be called upon to withstand the 
hardest buffets of Father ^N'eptune. If you strolled 
into a shipyard and asked for information, you might 
be much mystified by the names of things, as the most 
kindly of instructors would necessarily use at least 
some of the technical terms to which he has always 
been accustomed. 

However, it is impossible to keep a description of 
shipbuilding out of a book that deals wdth great feats 
of engineering, so I mean to make an attempt to give 
you a fair idea of how a monster ship is designed and 
built. 

In order to be well up to date I will select as 
example the huge quadruple-screw Mauretania, which, 
like her sister ship, the Lusitania, created such interest 
both inside shipping circles and out when she was 
laimched, and made her bid for the ^' blue ribbon " 
of the Atlantic. The Mauretania broke the record 




Fig. 39. — The mooring chains for the Mauretania I ;ij h link weighs 336 lbs. ; 
each common link, 243 lbs. ; swivel connection, 4,485 lbs. Total weight of 
moorings, 200 tons. Made by Messrs. Brown, Lenox, and Co., Pontypridd, 
Wales. 



76 THE BUILDING OF A BIG SHIP. 

in size as well as speed, being 790 feet long ^' over 
all/' 88 feet in the beam, and having a draught of 
33I/2 feet at a displacement of 38,000 tons. To drive 
this huge mass through the water at the contract speed 
of 25 knots per hour, 68,000 horse-power had to be 
developed by the engines, which — and this made 
these ships all the more interesting — were of the 
Parsons turbine type. Twenty-five boilers, weighing 
100 tons or so apiece, and affording between them 
3% acres of heating surface, supply the steam to 
work the six turbines. We shall come to a more 
detailed account of the machinery later on, and may 
therefore pass at once to some general remarks on 

THE PLANNING OF A SHIP. 

When the owners of a vessel that is to be have 
made up their minds as to her size, speed, and 
capacity, drawings have to be got out. These fall 
under two heads: (1) the sheer draught; (2) detail 
drawings, plans, and sections of the ship. 

To take them in order. The sheer draught 
consists of drawings showing the dimensions and 
shape of the vessel's outer surface hefore the plating 
is put on — that is, the outside dimensions of the mere 
framework. As a ship has length, breadth, and depth, 



THE BUILDING OF A BIG SHIP. 



77 



it is necessary that there should be three of these 
drawings, the measurements in which must coincide 
exactly. You may imagine, first, that the ship is 
cut down the middle from stem to stern, and each 
half further subdivided vertically lengthwise through 
planes parallel to the centre plane. The inside edge, 
as it were, of every one of these slices is shown in 
the elevation, or sheer plan. 

The elevation has parallel horizontal lines dra^vn 
from end to end at equal distances from one another. 
These are known as the '^ water lines,'' which we 
meet again in the half-hreadth plan, showing one- 
half (longitudinally) of the vessel as seen from above, 
with the curves which it has at the successive water 
lines. 

Then again the vessel must be considered endwise. 
On the " elevation " are equally spaced vertical lines, 
termed " square stations," from stem to stern. The 
body plan shows the curves that the vessel has if cut 
squarely across at these square stations. 

The lines of all kinds are carefully numbered for 
reference and comparison. 

The DETAIL DRAWINGS comprisc (a) the profile, or 
section from end to end, showing how the decks and 
bulkheads are to be placed; (h) the deck and hold 



78 



THE BUILDING OF A BIG SHIP. 



lolans, showing the various decks as seen from above ; 
(c) the midship section and other transverse sections 
needed to show the arrangement and sizes of the 

frames, platina:, and other parts used in construction. 




Fig. 40. — One of the Mauretania's anchors. Weight, about lu tons. Made by 
Messrs. N. Hingley and Sons, Netherton. 

It is therefore apparent that each sheer draught 
drawing has its counterpart among the detail draw- 
ings. It should be mentioned that they are all made 
on a reduced scale of l/2"iiich or 14-inch to the foot, 
so there is all the greater need for absolute accuracy 



THE BUILDING OF A BIG SHIP. 



79 



in order that the enlarged drawings — of which we 
shall speak presently — may be " fair." 

In the case of a vessel which in design, size, and 
speed is to differ from existing examples, it is neces- 
sary for the designers or builders to make experiments 
with a model before finally deciding on dimensions, 
lines, power of engines, etc. 



THE EXPEKIMENTAI. MODEL. 

This is usually a wooden block or a holloAv casting 
of paraffin wax, shaped to the contours of the sheer 
draught by special machines. When it has been 
finished and polished, it is transferred to an exper- 
imental tank,^' and loaded until it sinks to a certain 
level. A large carriage spanning the tank tows it 
through the water at speeds which are mechanically 
recorded, as are also the pull required to move the 
model at any given speed, and many other particulars. 
If the resistance proves to be excessive the shape of 
the model is altered until it gives satisfactory results ; 
and from it the final designs are made. 

In the case of the Mauretania the wax model was 
supplemented by a large launch, 4:7^2 ^^^^ long, 

* That at Haslar, near Portsmouth, used by the British Admiralty, 
is 400 feet long, 20 feet wide, and 9 feet deep. 



8o 



THE BUILDING OF A BIG SHIP. 



driven by electric accumulators and motors carried 
on board, run in a large dock on the river Tyne. It 
was built of wood, and so constructed that its shape 
and the positions of the propellers could be modified 
within certain limits. Bj means of delicate instru- 




FiG. 41. 



-Huge planer for ship's plates. Messrs. Wm. Sellers and Ck). 
Philadelphia. 



ments information of many kinds was collected as 
regards the best shape of the stern ; the effect of wind ; 
the best relative position, speed, and curvature of the 
pro^^ellers; friction of the launch's surface against 
the water, etc. In passing it is interesting to notice 
that the several designs of propellers recommended 



THE BUILDING OF A BIG SHIP. 8i 

by different authorities as the most efficient were 
found to vary among themselves by as much as 12 per 
cent, in their actual efficiency. In the case of a ship 
of the size of the Mauretania the wastage of 12 per 
cent, of its engine power would mean a huge extra 
coal bill every trip, and the experiments would have 
been justified had they only served to prevent such 
a loss of power as the adoption of a bad design of 
screw would have occasioned. 

THE BUILDING-SHEDS. 

The task of building the Mauretania s hull was 
entrusted to Messrs. Swan, Hunter, and Wigham 
Richardson, Ltd., of the Wallsend Shipyard, N^ew- 
castle-on-Tyne. As the vessel was to be much larger 
than any — the Lusitania excepted — that had ever 
been launched, it was necessary to lay doAvn special 
building-berths for the purpose. The vast sheds, 
under one of which the Mauretania came into being, 
are 750 feet long, 150 feet high, and 100 feet wide 
inside. As the roof is glazed work can be carried 
on in all weathers without discomfort, and powerful 
arc lamps give sufficient light for the men to j)ly their 
tools by night. A notable feature of the berth is the 
arrangement of cranes, which (see Fig. 42) run under 



82 



THE BUILDING OF A BIG SHIP. 



the roof on rail girders attached to the beams. Loads 
of 40 tons can be picked up bj these cranes if several 




Piling for Door 



Fig. 42. — Diagram of shed in -n-hich the Mauretania Tvas built at the Wallsend 

Shipyard, h R = hydraulic riveter ; b b = bilge blocks ; k b = keel blocks. 

(By permission of "The Shipbuilder.") 



be used in concert. The dotted lines in the diagram 
indicate booms from which hydraulic riveters, h k, 



THE BUILDING OF A BIG SHIP. d>T, 

are suspended while at work on the rivets of frames 
and plates. 

Adjacent to the berths are the workshops, furnished 
with all the most modern machinery for handling bars, 
frames, and sheets of steel — powerful punches, shears, 
planers, drills, hammers, presses, etc. 

On account of the immense weight of the hull, the 
floor of the berth had to be prepared with the greatest 
care. First of all some 16,000 piles of timber, 13 
inches square and averaging 30 to 35 feet in length, 
were driven down into the ground. Along the top 
of these were laid great beams, and on them again 
a complete floor of thick planks. 

In the centre of the floor the shipwrights arranged 
the keel blocks (Fig. 42, k b) in groups of five, there 
being a 3-foot interval between every two groups. 
The cap-blocks, on which the keel actually rests, were 
of stout oak. A straight line drawn along the top of 
the blocks had a downward gradient towards the river 
Tyne of about half an inch in the foot, and an average 
distance of five feet from the ground. The reader 
will understand without explanation the necessity for 
laying the keel on the slope, in order that, when the 
time for launching the ship comes, the mass may be 
helped into the water by its own weight. 



84 THE BUILDING OF A BIG SHIP. 



THE STEUCTUEE OF A SHIP. 

It is now time to saj something about the actual 
structure of a ship, and to explain terms commonly 
used for the various parts. The hull of a ship is 
in essence a steel or iron box of curious shape. It 
is, in fact, a girder of the strongest kind, as it needs 
to be, seeing that at one moment it may be in the 
trough of a wave, deeply imnaersed fore and aft only, 
and the next riding on its crest with bow and stern 
almost out of the water. It has, too, to withstand the 
terrific blows of ocean billows, which tend to bend 
it sideways. 

Putting the machinery on one side for the moment, 
the steelwork of a ship falls under three headings. 
{a) The skeleton; (&) the skin; (c) internal divisions. 
The skeleton, or framework, consists of a great back- 
bone, the heel and centre girder, running from end to 
end, from which spring at intervals on both sides ribs, 
called frames, which curve upwards, and are con- 
nected and held together by horizontal rafters, the 
beams, carrying the decks. 

There are many systems of framing a ship, each 
adapted for a certain purpose. The structure of a 



i. 



THE BUILDING OF A BIG SHIP. 



85 



warship differs widely in some respects from that of 
an Atlantic liner^ and the liner in turn differs from 
the purely cargo boat, which must have very capacious 
holds. As we cannot command sufficient space for a 
detailed description of these various types, we will 



upper Deck 



Main Deck 



■J 7 



Lower Deck 



"^SCr/ngei 






-J 








:r4 












/ 




k 


■^ 


\ 




1 
J 


2 

e 

1 


Centre Cirde 


r 


J / 


// 



Fig. 43. — Midship section of the Mauretania. o s = outside strake ; 
I s = Inside strake. 

confine ourselves at present to the passenger vessel, 
the class to which the Mauretania belongs. 

Let us now consult Fig. 43, showing half of a 
midship section of our big ship. First we notice the 
keel, a flat plate 50 inches wide and 31/4 inches thick. 



86 THE BUILDING OF A BIG SHIP. 

which runs along the centre of the vessel, and forms 
its lowest part. Above the keel, and also running 
fore and aft, is the centre girder, 60 inches high and 
1 inch thick. On either side of the centre are seven 
other longitudinal girders, the outermost of which 
is known as the margin plate. These fifteen girders 
stiffen the bottom fore and aft, and the -floors (which, 
be careful to note, are plates stood on edge) running 
athwart the bottom connect the girders and stiffen the 
bottom of the framing from side to side. The floors 
are riveted at their bottom edges to the frames, which 
are carried upwards beyond the margin plates to the 
tops of the vessel's sides, and at their upper edges to 
the reverse frames. In the middle part of the ship 
the floors are 32 inches apart, but towards the ends the 
distance decreases to 25 inches. 

The bottom of the vessel is plated both above and 
below the floors, so as to form a number of water- 
tight chambers extending from the margin plate on 
one side to that on the other. Some of the floors 
are pierced with large holes, so that men may pass 
along the double bottom to examine the plates when 
necessary. The double bottom can be filled with 
water to act as ballast in lieu of a cargo, and also 
affords valuable protection in case of injury to the 




Fig. 44. — The Mauretania at an early stage. View looking forward from after- 
end of engine-room. 
(Photo. ''The ^'lii uhiuldcrr^ 



88 THE BUILDING OF A BIG SHIP. 

outside plates. Many a vessel has been saved by ber 
double bottom. 

.Above tbe margin plate rise the continuations of 
the frames, channel bars of [ section, 10 inches deep. 
Every fourth frame is much deeper, to give additional 
strength to the sides. These frames are connected 
horizontally by the stringers (corresponding to the 
longitudinal girders of the bilge) to which are attached 
the stringer plates forming the margin of the decks, 
and stiffening the framework laterally, besides serv- 
ing to connect the teams to the frames and shell plates. 

The beams are supported by pillars and bulkheads, 
the latter being vertical watertight partitions, which 
divide the interior of the ship into separate chambers, 
as it were. If the sides of the vessel are breached 
the bulkhead doors are closed, and the inrush of water 
is confined to that compartment in which the breach 
occurs. 

To resume: the skeleton of the vessel has longi- 
tudinal girders and stringers, connecting the cross- 
floors and frames, which in turn are held together 
laterally by the deck-beams, bulkheads, etc. 

THE SKIN OF THE SHIP 

is a number of steel j)lates of varying thickness and 



THE BUILDING OF A BIG SHIP. 



89 



size. Amidships the Mauretanias plating is 1 inch 
thick, except near the keel, where it is 1 ro inch thick, 
and at the tops of the sides, which, having to bear the 
heavy strains of " hogging " and " sagging," carry 
plates of double thickness. The diagram, Fig. 45, 



M 





Fig. 45. — Diagrams to show " hogging " and " sagging " of a ship, and the 
points at which a rupture is most likely to occur. 

will explain the meaning of the terms " hogging " and 
" sagging.'' 

The plating is laid on the frame in strokes, which 
correspond to the courses of bricks in a wall or of 
boards in a wood-covered house. In Fig. 46 a strake 
has been marked in solid black to give the reader a 
clear idea of what it signifies. Each strake is com- 
posed of a number of long plates joined by their 



90 THE BUILDING OF A BIG SHIP. 

ends. The heaviest plates of the Maureiania are 48 
feet long and weigh from 4 to 5 tons each; the ordi- 
nary plates are 34 feet long and of 2% to 3 tons 
weight. 

Up the sides (see Fig. 43) every other strake is 
laid next to the frames. These are the '^ inside " 
strakes. The alternate^ or ^' outside " strakes, which 
overlap the inside along the edges, necessarily stand 
away from the frames, and these gaps have to be 
filled up with packing-pieces.. The bottom frames 




Fig. 46. — Ship in cradle. The thick black line indicates a " strake " of 

plating. 

of the double bottom are '^ joggled " — that is, bent 
at intervals so that the plates may here be laid on 
clinker fashion, the bottom edge of each strake over- 
lapping the top edge of that next to it on the keel 
side, and no packing-pieces are required for that part 
of the shell. 

THE SHIPWRIGHTS AT WORK. 

After this preliminary canter we will return to 
the plans of the ship. A ^^ half -breadth " model in 
wood is made from the reduced scale drawings, and 
on it are '^ laid off '' the sizes of the plates by lines 



THE BUILDING OF A BIG SHIP. 



91 



which show the edges and butts (the end joints) and 
the position of the stringer plates. Every strake is 
given a letter, and the plates of each strake are num- 
bered consecutively from stem to stern. Erom the 
model are calculated the dimensions of the frames 




Fig. 47. — Autnmolnle^ JriTiug two abreast through the Mauretanla's funnels. 
(Photo, "The Shipbuilder.") 

and plates, which are entered in lists to be forwarded 
to the manufacturers of iron or steel. A little extra 
length and width is allowed to plates " in the rough," 
and extra length to the frames, to permit of trimming 
to exact size when the parts are assembled. 



92 THE BUILDING OF A BIG SHIP. 

While tbe order is being executed by the steel- 
makers, tbe lines of tbe sbip are enlarged to full size 
on tbe floor of a spacious moulding loft, from wbicb 
tbe sbape of tbe frames is transferred to tbe scrive 
hoard, sl large wooden floor situated near tbe furnaces, 
made up of a large number of seasoned deals secured 
edge to edge by clamps. 

On tbe scrive board will be found a full-sized body- 
plan (see p. ), sbowing (a) tbe outer edges of 
tbe frames, (h) tbe upper edges of tbe floor plates, (c) 
tbe edges of tbe sbell plates (tbe skin of tbe vessel), 
and otber details wbicb it is not necessary to mention. 
Tbe lines are scratched deeply into the wood, and 
painted different colors so that they may be distin- 
guished easily. 

ASSEMBLING THE FRAMEWORK. 

The keel having been laid, tbe centre girder is 
attached to it by means of angle bars, the parts 
having been punched with rivet boles previously. 
The positions of the transverse frames are then care- 
fully marked and numbered in rotation from the 
stern forwards. 'Next follows the bending of the 
frames and reverse frames. This is effected on a 
bending slab (Fig. 48), made up of a number of 



THE BUILDING OF A BIG SHIP. 



93 



square blocks of cast-iron five inclies thick, and 
pierced with holes in regular lines and at equal 
intervals. First, a strip of thin iron, called a set- 
iron, is bent on the scrive board to the exact curve of 
the frame. Second, the set-iron is taken to the bend- 
ing slab, on which its curvature is marked with a 






Fig. 48. — Iron slab for bending the frames of a ship. The small circles are 
holes. D D = clogs ; B L = bending lever. 

piece of chalk. Another line is drawn parallel to 
this, inside it, as far away as the frame is deep, and 
the set-iron is readjusted so as to have its outer curve 
on this line, allowance being made for the fact that 
a bent angle-bar straightens somewhat as it cools. 
Pins are driven into the holes in the slab nearest the 
inside of the set-iron, and the gaps filled up with 



4 



94 THE BUILDING OF A BIG SHIP. 

packing-pieces of various shapes until the iron has a 
firm support at the back from end to end. Third, 
the frame angle-bar is heated in a furnace to a bright 
red and taken to the slab, where it has one end pinned 
tightly up against the corresponding end of the set- 
iron, and is bent to shape by means of levers or 
hydraulic presses. It is held down to the slab by 
bent pins, called "dogs" (Fig. 48; t>, t>, d), driven 
into the slab holes. 

The frames are bent in pairs, one for each side 
of the keel, from the same set-iron. After bending 
comes " proving " on the scrive board, and any 
necessary adjustment of shape. 

Similarly with the reverse frames. 

It would be wearisome to follow out in detail the 
fixing of the longitudinal girders, floors, and frames, 
and their riveting. Suffice it, therefore, to say that 
the utmost care has to be exercised to secure proper 
alignment. Every rib must be parallel to the rest, 
and also square to the keel, both laterally and verti- 
cally. As the keel is laid on the slope, the " plumb- 
ing " of the frames so that they shall be perpendicular 
to the keel is a matter of some difficulty. Measure- 
ments in all directions are constantly checked before 
the riveting is done and the frames fij^ed finally. 



THE BUILDING OF A BIG SHIP. 



95 



After the frames, the longitudinal stringers are 
placed in position, and the deck beams set athwart- 
wise. The Stem Bar, for the bows, and the Stei^n 
Frame, aft, are joined on, and then* the skeleton 
work of the ship is ready for 




Pig. 49. — First days on a battleship. Fixing the vertical keel on to the outer 
and inner keel to receive the bracket stays. 
iPhoto, Stephen Cribb, Southsea.) 



THE PLATING. 

The placing of the many plates is also a rather 
complicated business. The girth of the ship amid- 
ships is much greater than near the bow and stern, 

* The plating of one part of a ship is often commenced before the 
framing is complete, in order to save time. 



96 THE BUILDING OF A BIG SHIP. 

consequently the area of plating tapers away fore 
and aft, and the breadth and number of strakes must 
be suitably decreased. 

The inside strakes are put on first. For every 
plate a pattern or template of thin boards is made, 
somewhat larger than the plate. It is clipped in 
place on the frames by bent irons, and on it are 
marked the edges of the butts (the parts which over- 
lap, or are overlapped by, the adjacent plates in the 
same strake), the edges of the plate, and the position 
of the rivet holes in the frames to which the plate 
will be attached. The template is removed and 
clipped to the steel plate, to which the positions of 
the frame and rivet holes are transferred in white 
paint. Then the rivet holes for the edges and ends 
are marked, and the plate is punched, planed at the 
edges, ^nd bent to the shape of the frames. Where 
there is much curvature special templates are made, 
and the bending is continued until the 2:)late is ^^ fair " 
with these. 

The inside strakes having been bolted into position 
on the frame, the outside strake templates are pre- 
pared in like manner, and the . plates marked and 
punched ; then follows 



THE BUILDING OF A BIG SHIP. 



97 



THE EIVETING^ 

whicli is performed as far as possible with mechanical 
tools. As it is necessary that all outside rivets should 
be absolutely watertight, great attention is giyen to 
their shape and to that of the riyet holes. Every 
rivet is carefully inspected after being closed, and 
all faulty ones replaced."^ The arrangement of the 
plate joints is not so simple as might be thought, as 
the overlapping joints of an inside strake do not give 
a flat seating for the adjacent outside strake plates. 
The difficulty is overcome by scarfing, or bevelling 
off the plates at such points, so that they may 
interlock. 

When the riveting is completed, all the joints are 
caulked, or rendered watertight, by striking the pro- 
jecting plate edge till it swells and presses tightly 
against the plate below. The joints are usually tested 
by water under pressure. This done, the plates are 
scraped and painted. 

Simultaneously with the plating, the laying of 
decks and erection of bulkheads has been proceeding. 
The screw tubes, screws, and rudder have been placed, 
and innumerable jobs performed on the metalwork of 
the interior. The time is at hand for 

* In the Mauretania 4,000,000 rivets, weighing 700 tons, were used. 

7 



98 THE BUILDING OF A BIG SHIP. 



PEEPARATIOl^S FOR THE LAUNCH^ 

the most critical'and anxiety-causing process of ship- 
building. Here is the monster hull of the Maure- 
iania, 16,000 tons in weight, resting on the keel blocks 
and the bilge blocks on either side (see Fig. 42), and 
shored up by a huge number of poles. The problem 
is to get her into the waters of the Tyne, which at 
this point is barely as wide as the vessel is long. The 
shipbuilders were careful, we Inay notice, to set the 
berths at an angle to the river, and thereby gain some 
extra room for the launch of vessels such as this. 

Gangs of men set about preparing the launcliing 
ways, a huge wooden slide as long as the ship. The 
standing ivays are built up on the floor of the berth, 
and extend some way into the water on rows of piles. 
The upper surfaces of these ways, which are laid 
strictly straight and parallel at a distance of 25 feet 
from centre to centre, are six feet broad. In Figs. 
50 and 51 the standing ways are marked in solid 
black. You will notice that the outside edge of each 
standing way is somewhat thicker (two inches) than 
the rest, to form a guide for the sliding ways which 
carry the vessel. 



THE BUILDING OF A BIG SHIP. 



99 



Fore and aft, where the ship's sides are " fine " 
and far above the ways, cradles are built of large 
timber baulks (Figs. 52 and 53). The aft cradle 
grips the tubes of the inside propellers, while the 
timbers of the fore cradle rest at the top against 





Figs. 50, 51. — Sections through launching cradles, amidships, and in way of 
cradle. The solid black portions are the standing-ways. Observe the 
wedges for raising vessel off keel blocks. 

long shelf-plates attached to the sides of the ship. 
The cradle timbers are tied together to make a 
practically solid mass. 

As there are no rollers in the structure, tremendous 



lOO 



THE BUILDING OF A BIG SHIP. 



friction would be set up between the fixed and 
moving ways, unless the rubbing surfaces were well 
lubricated, so these surfaces are smeared thickly with 
greasy substances shortly before the launch. For the 
Mauretania 17,150 square feet of ways had to be 




Fig. 52. — Section of after-end of cradle. 



{From "The Shipbuilder.") 



Fig. 53. — Section at fore- 
end of cradle. The upper 
ends of the cradle tim- 
bers rest against an an; 
gle plate attached to the 
ship's side. 



lubricated with 14i/) tons of tallow, 22 cwts. of soft 
soap, and 113 gallons of train oil. 

In order to free the keel and bilge blocks the 
vessel's weight must be transferred from them to the 
cradles and ways. Referring to Fig. 51, you will 
see that between the top of the moving ways and 



THE BUILDING OF A BIG SHIP. 



lOI 



the bottom of the timbers next the vessel there are 
wedges sticking out on either side. When the time 
comes for freeing the blocks these are driven in, so 
as to force up the cradles and put the weight on the 
ways. 




Fig. 54. — The after-cradle of the Mauretania. Observe the huge size of 

the propeller. 

{Photo, suppUedby "The Shipbuilder.' ') 

It has been mentioned that the Tyne is a narrow 
river. Care must be taken that the stern of the ship 
does not strike the opposite bank, which is less than 
1,200 feet from the end of the ways. In order to 
bring the ship up quickly after she is fairly afloat, 



I02 THE BUILDING OF A BIG SHIP. 

long cables are attached at one end to the ship and 
at the other to piles of chains and armor plates. 

Diagram 55 shows the five 80-ton chain piles and 
one 100-ton plate pile on each side of the keel. The 
chains are laid out in squares, which have to be dis- 
torted before they will move. This prevents sudden 
jerks, or, to use more technical language, ensures that 
the load shall be taken on gradually. It is arranged 
that the drags shall come into action successively — 






cBt^HQ^M^^' 



Fig. 55. — Sketch showing arrangements for launching the 2Iauretania. c c = 
ten 80-ton piles of chain ; a p, a p = two 100-ton piles of armor plate. 

the first 30 feet before the vessel leaves the ways, the 
last when her bows are 90 feet away in the river. 

THE LAUNCH. 

"All is finished! and at length 
Has come the bridal day 
Of beauty and of strength: 
To-day the vessel shall be launched!" 

The town makes holiday, and its inhabitants swell 
the mighty crowd of sightseers that have collected to 
witness the great event. Gangs of workmen, swing- 
ing huge hammers in time to a chorus, knock away 
the great shores, which fall one after another with a 



THE BUILDING OF A BIG SHIP. 



103 



crash, and drive in the wedges to transfer the vessel's 
weight from the blocks to the ways. Meanwhile 
hundreds of carpenters are busy under the keel, plying 
their trade by the light of smoking torches. 

A telephone message from the yard foreman to 
the stand where the most illustrious sightseers are 
gathered tells that all is ready. A bell rings sharply, 
and an electric button is pressed. A moment later 
four hydraulic rams release the eight '' triggers " 
which have prevented the ship moving, and the 
Mauretania begins her smooth passage to the water, 
slowly at first, but quickly gathering a speed of 15 
miles an hour. Her stem^ is immersed ; it floats ; the 
water foams high before it. The wreckage of the 
ways and cradles covers the surface. Surely she will 
ground on the opposite bank ! 'No ; the trusty cables 
tighten, and one after another pull on the drags, the 
united weight of which brings her up 90 feet from 
the ways, within a few yards of the desired spot. 
Surely a triumph of calculation! From start to 
finish the business has occupied but seventy fateful 
seconds. The crowds which have held their breath 
in expectation now burst out into wild cheering, while 
fussy little tugs puff up and take the great hull off to 
the moorings prepared for her. 



THE BUILDING OF A BIG SHIP. 105 

The launch is over ; the huge berth that has housed 
her for many long months looks astonishingly empty. 
The first chapter of the Mauretanias existence has 
ended happily — more happily than in the case of the 
transatlantic liner Princess Yolande, which, during 
its launch at Genoa in September, 1907, capsized and 
sank under the eyes of a large crowd. 

THE ENGINES OF THE BIG SHIP. 

The second chapter deals with the installation of 
the machinery in the hull, and the completion of its 
internal and external fittings. Some 15,000 tons of 
dead weight have yet to be added. 

We will adjourn in imagination to the yards of 
the Wallsend Slipway and Engineering Company, 
where the construction of the huge turbines and 
boilers has been in progress simultaneously with the 
building of the hull. In the boiler shop, 220 feet 
wide and of an average length of 290 feet, stand the 
huge boilers, twenty-three of which contain eight 
furnaces each, four at either end, and two four 
furnaces each, making a total of 192 furnaces, which 
will consume many hundreds of tons of coal a day. 
Every boiler is 17% feet in diameter, and — except 
the last two — 22 feet long. The plates used for these 




-^p* ■'ili^ 





t -^^ 



THE BUILDING OF A BIG SHIP. 107 

great steam-raisers were of unusual size — 37 feet 
9 inches long, 7 feet 8 inches wide, and IJ inches' 
thick — and weighed 7 tons 3 cwt. 

These monsters have been put in place by the aid 
of 100-ton travelling cranes running on rails over- 
head. Before leaving the shop we may observe a 
huge plate-edge planing machine, which will take a 
continuous strip off a plate 35% feet long; the mam- 
moth bending rolls for handling plates 12% feet wide ; 
and a hydraulic riveter with a 12-foot '^gap."* 

In the erecting shop we find the huge turbines — 
six of them: four for driving the ship forward, two 
to take her astern. 

I^ow for a short description of these. The sizes 
of the rotors, or revolving parts of the turbines, are 
as follows: The high-pressure (which receive the 
steam direct from the boilers) are 96 inches in diam- 
eter, have blades ranging from 2% to 12 inches in 
length, and weigh 72 tons each with the shaft. The 
low-pressure (which take steam from the high- 
pressure) are 140 inches in diameter, have blades 
8 to 22 inches long, and weigh 126 tons each. The 
astern (also high-pressure) are 104 inches in diam- 

* That is, 'one having arms long enough to close a rivet in a hole 
12 feet from the edge of a plate. 




Fig. 59. — Low-pressure turbine, showing top half of casing lifted. 
(Photo, The Wallsend Slipway and Engineering Co.) 




Fig. 60. — Low-pressure turbine rotor, fully bladed. 
{Photo, " The Shipbuilder.") 



no THE BUILDING OF A BIG SHIP. 

eter ; tlieir blades range from 2 to 8 inches in length ; 
weight, 60 tons. The drum, of each of the high- and 
low-pressure rotors is compounded of three great rings, 
lathed inside and out, screwed and shrunk together. 
The astern drums are made up of two rings only. 

As for the turbine casings, their lengths '' over all " 
are 45 feet 8 inches, 48 feet 2 inches, and 30 feet 
1^ inches for the high-pressure, low-pressure, and 
astern turbines, respectively. The casings were com- 
pounded of six castings each,, three for the top half 
and three for the bottom, each casting being care- 
fully machined so as to make a perfect fit with its 
neighbors. 

The shafts are 3 feet in diameter for the high- 
pressure, 4 feet 4 inches for the low-pressure, and 
3 feet 3 inches for the astern turbines, and all hollow. 

The blades, of which there are many thousands in 
each turbine, were built up in segments (Fig. 61), 
ten of which made a complete ring (Fig. 62). The 
foundation of each segment is a slotted curved bar, 
which, when the blades are all in position, is fixed 
into an annular groove in the drum by means of 
strips of metal driven tightly in between it and the 
sides of the groove. This method of blading was 
found to be very much more expeditious than the 




Fig. 61. — A segment of blading for turbine rotor. 
{Photo, The Wallsend Slipway and Engineering Co.) 




Fig. 62. — Complete circle of blading for rotor. 
(Photo, " The Shipbuilder.-') 



112 THE BUILDING OF A BIG SHIP. 

older system of keying the blades directly into the 
drum. The rings of fixed blades, which alternate 
with the rotor rings, were attached to the inside of 
the casing in a similar way.* 

FITTING OUT THE SHIP. 

A huge 150-ton floating crane transferred the 
boiler, turbines, and other machinery from the makers' 
yards — the parts of the turbines being of course 
separated for the process — into the lowest depths of 
the vessel, below the water-line. As they arrived 
they were assembled and made fast in place. Gangs 
of fitters supplied the boilers with their numerous 
fittings, and connected them up to the turbines, which 
in turn had their shafts bolted on to the propeller 
shafts. Then the huge " uptakes '^ to lead the furnace 
gases to the funnels were installed, and on the top of 
these the funnels themselves, four in number, one for 
each boiler-room. The funnels measure 23 feet 
7 inches from back to front, and are 16 feet 7 inches 
wide — are so gigantic, in fact, that while they lay 
in the builders' yard motor cars were driven two 
abreast through them (Fig. 47). Their tops are 153 
feet above the keel of the ship. 

* For a concise explanation of the working principle of the Parsons' 
steam turbine, see "How It Works," p. 79 and following. 



THE BUILDING OF A BIG SHIP. 



113 



After these, the auxiliary machinery of divers kinds 
— steering engines, pumps, draught and ventilating 
fans, evaporators, heaters, cranes, boat-hoists, fire- 
engines, djTiamos. In the passenger quarters car- 
penters, polishers, painters, plumbers, glaziers, up- 
holsterers, electricians, and other craftsmen were hard 
at work furnishing the hitherto empty spaces of the 
hull with the fitments of an ultra-luxurious hotel, 
down to a complete telephone installation with a 
capacity for two hundred stations and twenty exchange 
lines. The very clocks are of the most modern type, 
the forty-five distributed over the ship being worked 
electrically from a centrally-placed master-clock, 
which, it is hardly needful to state, is kept strictly 
to time. 

In the kitchens are ranges with a total frontage 
of 70 feet, and manifold labor-saving appliances. 
The bakers' and confectioners' shops contain all the 
apparatus that any reasonable maker of bread and 
pastry could possibly desire. Among the contents of 
the pantries are 3,000 pieces of '^ hollow ware " — 
dishes, tea and coffee pots, tureens, etc. — and 16,000 
spoons and forks — a huge number indeed, but none 
too large for the maximum population of this ocean 
leviathan, 

8 



114 



THE BUILDING OF A BIG SHIP. 



The splendid lifts to transport passengers from 
deck to deck; the gorgeous saloons and dining-rooms; 
the princely suites of staterooms ; the gymnasium ; the 
children's nurseries — on these and a host of other 
notable features we should like to dilate, but space 




Fig. 6.3. — A 150-ton crane lifting a submarine. 
{Photo, Messrs. Vickers Sons and Maxim.) 

forbids. We must hie us back to the engineering 
aspect of the Mauretania. 

When the vessel has all its machinery in place and 
connected up, steam is raised and the engines are 
given a docJc trial for twenty-four to forty-eight hours, 



THE BUILDING OF A BIG SHIP. 



115 



the ship being made fast to the wharf so that she 
cannot move. During this trial the action of all parts 
of the machinery is carefully watched, records are 
taken, and any defects are put right. 

Then comes a trial in the open sea, to see how 
she behaves when ''^ allowed to rip,'' what the speed 
is, and how much fuel she burns to produce it. The 
next item on the programme is to dry-dock her, and 
clean and paint the bottom, to prepare her for 

THE OFFICIAL TRIALS 

of forty-eight hours under full pressure. When so 
large a boat as the Mauretania has to prove herself, 
public interest is stimulated, and the results of the 
trial eagerly awaited. The Mauretania s trial took 
place between Corsewall Point in Scotland and Land's 
End in Cornwall, a distance of 300 knots, two 
southerly and two northerly trips being made. The 
results exceeded all expectations, and broke all pre- 
vious merchant-ship records handsomely. The average 
speeds of the four runs were as follows : — 

KNOTS. 

First run, Corsewall Point to Land's End 26.28 

Second run, Land's End to Corsewall Point 25.26 

Third run, Corsewall Point to Land's End 27.36 

Fourth run, Land's End to Corsewall Point 25.26 

Average speed throughout 26.04 



ii6 THE BUILDING OF A BIG SHIP. 

The third run was an extraordinary performance, 
with its average speed of 31% miles an hour for 
300 knots, and this attained, not by a slim, snaky 
torpedo destroyer, but by a floating mass displacing 
36,000 tons of water! 

Years ago Ruskin wrote that a ship of the line was 
the most honorable thing that man, as a gregarious 
animal, had ever made. To use his own words: 
'^ Into that he has put as much of his human patience, 
common sense, forethought, experimental philosophy, 
self-control, habits of order and obedience, thoroughly- 
wrought handiwork, defiance of brute elements, care- 
less courage, careful patriotism, and calm expectation 
of the judgment of God, as can well be put into a 
space 300 feet long by 80 feet broad." If the ship 
of his time stirred him to such enthusiasm, what, we 
wonder, would he have said of the vast merchant- 
ships and monster warships of to-day, filled from 
stem to stern with the most complex machinery, and 
capable of speeds which dwarf those of a few decades 
ago? 



Chapter IV. 
BRIDGE BUILDING. 

Bridge versus tunnel — The development of the bridge — Plank bridge — 
The open-work girder or truss — The bowstring girder — The 
arch — The suspension bridge — The cantilever principle — De- 
velopment of same — Advantages of the cantilever. 

WHEE" a road or a railway has to be carried from 
one bank of a river to the other, the engineer 
must choose between a tunnel and a bridge. In ninety- 
nine cases out of a hundred the bridge is selected 
without hesitation; but in the remaining one case the 
engineers may have to make long calculations of cost, 
and set one thing against another, and generally think 
the question out very carefully before they can come 
to a decision. In several of the great cities of the 
world through which an important river flows — 'New 
York and London are conspicuous examples — both 
bridges and tunnels are used, as at one point a bridge 
may be constructed more economically than a tunnel, 
and at another point natural conditions may favor the 



ii8 BRIDGE BUILDING. 

tunnel. The Niagara and Zambesi gorges, with sides 
precipitous and not very far apart, are eminently suited 
to bridgework, and a tunnel would here be quite out of 
the question. But at certain places on the Thames, 
where the banks are low, a tunnel '^ fills the bill " 
better than a ship-impeding bridge. 

Big bridges afford such splendid examples of the 
engineer's skill that you will like to know how they 
are built. Those tall, upstanding towers, massive 
piers, huge cables, far-reaching girders, gigantic 
arches, whan an infinity of labor they represent! 
Well may you admire the patient scheming and dogged 
struggle which went to their making. 

THE DEVELOPMENT OF THE BEIDGE. 

Let us begin at the beginnning — that is, with the 
simplest forms of bridge, and trace its development 
into the great structures of masonry and steel which 
span our rivers. 

Fig. 64 is a type which we know very well — a stout 
plank thrown across a ditch. As you walk over it 
it bends distinctly, and you donH like any one else to 
step on until you have reached the other end. Such 
a bridge would not stand heavy loads. But set a 
couple of such planks on edge joist-wise, as in Fig. 



BRIDGE BUILDING. 



119 



65, and lay short planks across them, and you have a 
bridge over which a horse and cart might pass safely, 
because long flat bodies of wood, metal, or other hard 





Fig. 64. — A plank bridge. 

'I'll'' I r— r 




FiG. 65. — Bridge of planks laid joistwise, and covered with cross-pieces. 




Fig. 67. — A steel girder. 



substances will stand a much greater strain joist-wise 
than plank-wise. The reason for this is shown in 
Fig. QQ, which represents a bent plank. Only the 



I20 BRIDGE BUILDING, 

middle part, h, retains its original length. The upper 
edge is shortened and the lower edge lengthened by 
bending; and the further a and c are from h the 
greater will be the resistance of the plank to bending. 
A plank 6 inches by 1 inch in section set on edge 
would stand a greater weight than two planks 3 inches 
by 1 inchj and these in turn would be much stronger 
than six battens 1 inch square. It must be remem-. 
bered, however, that our plank loses in rigidity in 
one direction as it gains rigidity in another, assum- 
ing its bulk to remain unaltered. The wider it is 
the thinner it must be. Now look at Fig. 67, which 
represents a piece of I-section steel bar. The flat, 
broad edges give it lateral strength, while the deep, 
upright part makes it very strong vertically. An 
ordinary railway rail is a girder of this type. Notice 
before passing on that the top and bottom edges of 
such a girder are named flanges, the central upright 
part the weh. 

For spans of 125 feet or less a solid built-up plate 
girder of type Fig. 67 is used. When that length is 
exceeded the solid is replaced by 

THE OPEN-WOPav GIEDER OR TEUSS^ 

built up of plates and bars. This is stronger in pro- 



BRIDGE BUILDING. 



121 



portion to its weight than is a solid- web girder, because 
all snperfliions metal is excluded, and what is used 
is so disposed as to give the best results. 

The truss derives its strength from the fact that 
three bars joined together to form a triangle resist 
distortion. Let us consider Fig. 68 for a moment. 

a 




Fig. 68. — Plank supported by inclined struts. 

a 




This shows a plank suspended by a bar a d from two 
inclined beams a h, a c meeting over its centre, their 
lower ends resting on the ground. 

If the plank be loaded the stress will be thrown 
on to the struts a h, a c, which cannot be pulled down 
without spreading their lower ends. Consequently, 



122 



BRIDGE BUILDING. 



if the ends be firmly supported, this simple bridge 
will carry a heavy weight. The same stiffness is 
obtained in a somewhat simpler manner by joining 
planks and struts, as in Fig. 69, to form a triangle 
t 




Fig. to. — Compound triangulated truss. Member in compression denoted 
by thick lines. 




ah c. E'ext we join several triangles together (Fig. 
70). A weight suspended from the middle would 
tend to bend the lower chord, e fghh, and bring the 
apices of the triangles nearer to the central vertical 
line. This is prevented by the stout upper chord, 



BRIDGE BUILDING. 123 

ah c d. The bars or beams that are in compression 
are marked thick, those in tension thin. Fig. 71 
shows the girder turned upside doT\Ti. The positions 
of the tension and compression members, as they are 
called, are reversed, ah c d being now in tension and 
e f g JiJc in compression. 

Before going further we must observe that the 
horizontal upper and lower parts of a truss are called 
chords; the vertical braces, posts; the sloping braces 
which have to withstand compression, struts; and 
braces in tension, ties. 

Fig. 72 is another form of the truss compounded 
of triangles, and in Fig. 73 we see a combination of 
the preceding two. 

The Bowstring Girder (Fig. Y4) is another form 
of truss, having a curved compression chord and a 
straight tension chord. Sometimes a " bowstring " 
is incorporated with a lattice girder of the type shown 
in Fig. 73. 

THE ARCH 

(Fig. 75) also contains a curved compression chord, 
but, unlike the truss, it has no tension chord, the 
latter being replaced by the resistance offered by the 
abutments against which the ends of the arch press. 



124 



BRIDGE BUILDING. 



At I^iagara may be seen a very fine instance of the 
arch bridge. 



Fig. 73. — Lattice-work truss, a h c d = panel; a 1), c d- 
posts ; 6 c = strut ; a d = tie. 




For spans exceeding 600 feet the arch or truss 
supported at the ends only is seldom used. 

Some of the longest spans in the world — 1,500 feet 
and more — are found in 



THE SUSPENSION BEIDGE. 



Fig. 76 is a very crude bridge of this kind — just a 
couple of ropes slung across a gorge and transverse 
bars laid on them. It has little stability, its curves 



BRIDGE BUILDING. 



125 



changing as the load moves, and on account of its 
^^ dip/' which has to be considerable to relieve the 
strain on the cables, is not suited for heavy traffic. 

Fig. 77 is a suspension of a more scientific design. 
A level roadway is suspended by ties from the cables, 
which are attached to anchorages at a higher level. 





Girdor lT\ I ^■>.. 

7^ 



A y 



FiG. 78. — Steel suspension bridge, a a = anchorages ; t t = towers, or 
supports. 

And then we pass on to Fig. 78 and the modern engi- 
neer's suspension bridge. On or near each bank of 
the river to be spanned is built a high tower, t^ and a 
massive anchorage, a. Cables or chains are passed 
over the towers and anchored at each end, drooping 
between the towers to the level of the roadway, which 



126 BRIDGE BUILDING. 

runs on a continuous stiffening girder having a slight 
" camher " or rise towards the centre. Vertical and 
sometimes diagonal ties join the girder to the cables 
at regular intervals from end to end so as to dis- 
tribute the weight of the girder and its moving load 
over the cables as equally as possible. 

The suspension is practically a one-span bridge.* 
When the distance is too great for a single suspension 
span, and the points on which piers can be built to 
carry trusses are very far apart, recourse is had to the 

CANTILEVEE PEINCIPLE. 

If you turn up the word ^^ cantilever " in Webster's 
dictionary you will find that it signifies " a projecting 
beam, truss, or bridge unsupported at the outer end; 
one which overhangs." 

Once again let us trace development. Fig. 79 
shows two beams or cantilevers, a and h, with one 
end fixed firmly down and the other ends projecting 
into space. A third beam, c, laid across the gap, 
completes the bridge. 

The Chinese made use of the principle hundreds of 
years ago. Fig. 81 is a sketch of a very old Chinese 

* It sometimes has two shorter "shore" spans between the towers 
and the anchorages. 



BRIDGE BUILDING. 



127 



cantilever bridge. First the beams a a were placed, 
then the longer beams h h, then the still longer beams 

A. 




w^ 



¥ 



Fig. 79. — Diagram to illustrate the principles of the cantilever bridge. 




Fig. 80. — Cantilever bridge of three spans. 

c c, and finally d d, which reduce the gajo sufficiently 
for a short girder e to span it. 




Fig. 81. — Chinese cantilever bridge. 



Fig. 80 represents diagrammatically a more elab- 
orate system. The end cantilevers, a and d, are fixed, 
as in the first instance ; the other four are in pairs, 



128 



BRIDGE BUILDING. 



h and c, supported at the middle on the piers x and y. 
Three " suspended girders," a, b, and c^ bridge the 
gaps. 

In Fig. 82 we have the fully developed type, 
illustrated in the Eorth Bridge, the cantilevers of 
which are very deep trusses of a somewhat triangular 
shape arranged in pairs, with their bases formed by 




Fig. 82. — The cantilever principle elaborated. 



the side columns of lofty steel towers. The figures 
below correspond to the parts of the diagram imme- 
diately above. Chairs represent the piers on which 
the towers are built, and the two boys sitting on 
them the towers themselves. Each boy extends his 
arms and supports them by stout sticks resting against 
the seats of the chairs. From the ends of the inside 



BRIDGE BUILDING. 



129 



sticks is hung a board, to illustrate the suspended 
girder, whereon is perched a third boy. His two 
supporters are prevented from toppling over inwards 
by having the ends of the outside sticks attached to 
piles of bricks as anchorages. The series of canti- 
levers might be extended indefinitely provided anchor- 
ages formed the terminals. 




Fig. 83. — Arches built out on the cantilever principle. 




T777/777P7777/ 
Fig. 84. — Arches supported by " falsework " during erection. 

The great advantage of the cantilever system is, 
that the cantilever arms can be built out in pairs 
on either side of their towers, so as to balance one 
another during construction and be quite independent 
of external support. The principle is employed even 
in the erection of some bridges which when finished 
do not represent the cantilever type. Thus, the St. 

9 



I30 BRIDGE BUILDING. 

Louis Bridge, with three arched spans of over 500 
feet each, was built out on the balance principle (see 
Fig. 83) until the halves of the arches met. The 
ties suspending them from the temporary works built 
on the top of the piers were then removed. The 
usual 23lan of steel arch erection is shown in Eig. 84. 
'^ Falsework " is erected on piles driven into the river 
bed to give support to the steelwork till it is able to 
support itself, just as wooden " centres " are used for 
masonry arches. 



Chapter V. 
THE FOUNDATIONS OF A BRIDGE. 

Need for firm foundations — Three methods of obtaining them — The 
pneumatic caisson — Its use for the Forth Bridge piers — Sinking 
a caisson — The ejector — The hydrauHc spade — FiUing in a cais- 
son with concrete — Blasting — Deep work with the pneumatic 
caisson — "Caisson disease" — The deep, open caisson — Cofferdams 
— Pile-driving. 

WHATEYEE be its type — truss, suspension, 
cantilever, or arch — a bridge must stand 
on absolutely secure foundations, which shall not 
budge the fraction of an inch; and in the case of 
a very large bridge that portion of it which is below 
water or earth level, and out of sight and mind, often 
represents the larger part of the total difficulties and 
expense entailed in the construction of the whole. 

If the engineer finds rock ready for him, well and 
good, for rock is the best of all foundations. But it 
happens frequently that he is called upon to obtain a 
firm footing for a pier on the soft banks or in the 
treacherous bed of a river. He must delve down 



132 THE FOUNDATIONS OF A BRIDGE. 

through silt, clay, and quicksand, until he reaches a 
stratum sufficiently firm to suit his purpose. 

Generally speaking, there are three principal 
methods of sinking foundations in a river bed or 
through water-logged strata. The first employs the 
'pneumatic caisson, a huge diving-bell in principle; 
the second, the deep, open caisson; the third, the 
cofferdam. 

To take these in order, — 

THE PNEUMATIC CAISSON 

is a cylinder or coffer of steel or wood, closed at the 
top but open at the bottom, which carries a steel 
cutting edge. The caisson is loaded so as to sink by 
its own weight, while men working inside, under 
an air pressure sufficient to prevent water entering 
beneath the cutting edge, excavate the bed and send 
the '^ spoil '' up through air-locks, or, if the material 
be liquid enough, eject it through pipes. 

As a good instance of work of this kind we may 
take the sinking of the cylindrical pneumatic caissons 
on which two of the three huge towers of the Forth 
Bridge rest. A section of one of these caissons is 
given in Fig. 85. Built of steel plates, they some- 
what resemble gasholders in external appearance. 



THE FOUNDATIONS OF A BRIDGE. 



'^2,?> 



They had a diameter of 70 feet at the bottom, but 
tapered to about 60 feet at the top. Seven feet 
above the bottom edge an air-tight floor was formed, 




(Compressed Air') 

Fig. 85. — Section of one of the pneumatic caissons used for building the 
piers of the Forth Bridge. 

extending over the whole area up to the outer shell, 
and supported from above by four strong lattice 
girders reaching from side to side. Above the floor 
the caisson had an inner shell, concentric with the 



134 



THE FOUNDATIONS OF A BRIDGE. 



^ 



ZI 



HP 



outer, to which it was stayed. On the top of each 
caisson the engineers erected a temporary extension 
of the sides to exclude water at high tides, and in- 
side were built platforms for cranes, air-compressors, 
mortar-mixers, etc. Three shafts — 
two for materials, one for men — 
each furnished with an air lock 
(Fig. 86), connected the bottom 
chamber with the platforms. 

When complete, the caisson was 
launched and towed to the spot 
where it was to sink on to a bed 
previously prepared by divers. The 
roof of the air-chamber was then 
loaded with sufficient concrete to 
make the caisson settle and just 
prevent it floating at high tide. 
Pipes leading into the air-chamber 
through the floor above, and termi- 
nating in flexible nozzles, were then 
set to work to clear out the semi-fluid silt which 
formed the top of the river bed. A hollow hav- 
ing been dug in the ground, water was allowed 
to flow into it and mix with the more solid 
material until the proper consistency for ejection had 




Fig. 86. — Sections of 
air-lock. 



THE FOUNDATIONS OF A BRIDGE. 135 

been obtained. The man working the ejector then 
dipped the end of his bore into the sump till it was 
almost submerged. The high-pressure air of the 
chamber rushed up the tube with great velocity, 
carried with it some of the mixture, and expelled it 
in gulps. In this way the soft surface was stripped 
off. On reaching clay the ejector could be used for 
removing water only, and the men had to do genu- 
ine navvy-work, with spades and picks, loading 
the loosened materials into buckets running up and 
down the shafts. When hard boulder clay was 
struck, dynamite and powder were resorted to, 
but with little effect, as clay has no ^^ grain," and is 
too yielding for explosives to rend it as they would 
harder substances. To dig out this clay by hand 
proving impracticable, Mr. Arrol, the contractor for 
the bridge, devised a hydraulic spade, with a large, 
wide blade which a ram resting against the top of 
the chamber, drove deep down into the clay. This 
machine detached slab after slab, and gradually ate 
its way all over the area covered by the caisson. 
It was then arranged to undercut the edge, pillars 
of material being left at intervals to support the 
caisson at points all around the circumference, until 
the bearing surface could no longer sustain the 



136 THE FOUNDATIONS OF A BRIDGE. 

weight, and the caisson gradually cut its way do^vn 
through the pillars. Then the process was repeated, 
and the concrete load above the floor augmented to 
overcome the increased resistance of the clay. 

Great care had to be taken to ensure the caisson 
sinking on an even keel and in the correct perpendicu- 
lar line. From day to day it would tilt a little this 
way or that, and any tilt had to be rectified at once 
by undercutting at the opposite side of the diameter. 
At low tide, when the buoyancy of the caisson was 
least, and the danger of a sudden settlement great- 
est, the men were usually withdrawn; and wisely so, 
for on one occasion a caisson sank 7 feet, completely 
filling the air-chamber and part of the shafts. 

The greatest de]3th reached by one of these hy- 
draulic caissons was 89 feet below high- water level. 
The sinking occupied on an average about three 
months, and the amount of material excavated under 
each caisson was about 6,500 cubic yards. 

When a caisson had reached its final position, the 
chamber was cleared ready for filling with concrete. 
As it was necessary to maintain a high air-pressure 
to keep water out, and yet to send the concrete down 
quickly, the engineers removed the air-locks from the 
top of the material shafts, and fixed inside the shafts 



THE FOUNDATIONS OF A BRIDGE. 



fi i^kh 



137 




Fig. 87. — Construction of temporary caisson, Forth Bridge. In the back- 
ground is seen a complete caisson. 

IS-incli tubes reaching from the air-chambers to the 
platform on the caisson top, where the concrete- 
mixers were installed. Each tube had a flap top and 



138 THE FOUNDATIONS OF A BRIDGE. 

bottom. To pass down a charge of concrete the fol- 
lowing operations were performed. First, the men 
down below closed the bottom flap tightly, and sent up 
a signal that it had been closed. The workmen on the 
top then opened their flap, shovelled in concrete until 
the tube was nearly full, and closed the flap again. 
A signal having been passed down, the air-chamber 
gang turned a valve to admit compressed air into the 
tube above the concrete, and opened the lower flap. 
Out came the load with a rush, to be spread round 
the edges of the chamber. In course of time the space 
was filled completely, and after it the shafts. Finally, 
liquid cement was run in to occupy any existing 
cracks and crannies that the workmen had not been 
able to reach, and this part of the business was fin- 
ished. It remained to fill in the space above the 
chamber to low-water level with concrete, and to lay 
on the concrete the granite courses forming the top 
of the pier. As the weight of each tower of the bridge 
is distributed among four piers, there is very little 
danger of any settlement occurring. 

For some of the Forth Bridge piers a resting-place 
had to be cut in solid rock, below water. The work- 
men drilled holes by hand or with power drills, in- 
serted the explosive charges, connected them up with 



THE FOUNDATIONS OF A BRIDGE. 139 

wires leading .to an electric battery outside the cais- 
son, and withdrew. The closing of the circuit fired 
all the charges; and the chamber was cleared of the 
foul gases of the blast by forcing in a surplus quan- 
tity of air to drive the gases out under the cutting 
edges of the caisson. 

The same principle of the diving-bell has been used 
for the foundation of many famous bridges. The 
most notable feat of deep sinking under pressure 
must be placed to the credit of the men who built the 
piers of the great arch bridge that spans the Missis- 
sippi at St. Louis. Owing to the shifting and unsat- 
isfactory character of the river bed, the engineer, 
Captain J. B. Eads, decided that it was necessary to 
get down to the rock; and down to rock he sent the 
great caissons, though it meant that the excavators 
had to descend 110 feet below water level and work 
under an air-pressure of about 50 lbs. to the square 
inch. 

Labor at these great depths is far from pleasant. 
The large supply of oxygen enables men to work with 
unusual, though exhausting, energy; but only the 
physically strong can stand the strain for any length 
of time. Owing to the density of the air, voices 
sound harsh and metallic, robbed of all the small 



I40 THE FOUNDATIONS OF A BRIDGE. 

inflections that would differentiate them in the open. 
l^oises are exaggerated tenfold; what would be but a 
tap elsewhere has the sound of a heavy blow. 
Then there is a '^ caisson disease " — that scourge of 
folk who labor in high air-pressures. Its symptoms 
are severe pains at the joints when the air pressure 
is reduced to normal, and relief is obtained only by 
restoring the pressure. Investigations have traced 
the trouble to excessive absorption of nitrogen by 
the blood. In their hurry to regain the upper air, 
workmen are impatient of using the air-locks to 
decrease the pressure gradually enough to allow the 
excess of nitrogen to be expelled through the lungs. 
The result is that the gas, suddenly released, forms 
bubbles, which obstruct the flow of blood in the 
minute veins, and great local inflammation arises. 
Some Forth Bridge excavators were, we read, so pun- 
ished by the malady that they would voluntarily spend 
their holidays and Sundays in the caissons, to ease 
their swollen joints. Where proper care is used, 
"caisson disease'' is kept at bay, and in some works 
a gradual release from pressure is enforced. 

THE DEEP OPEN CAISSON 

is used for sinking to depths which would be unat- 



THE FOUNDATIONS OF A BRIDGE. 



141 



tamable by tbe pneumatic system. The caisson is 
usually divided by vertical 
partitions into tall, chim- 
ney-like chambers, all open 
at the top. Some of these 
chambers are closed at the 
bottom by sloping floors, 
terminating in a cutting 
edge (Fig. 88), and are 
filled up with heavy materi- 
als to give the structure suf- 
ficient weight; the others 
serve as shafts for mechani- 
cal dredges which scoop 
away the ground from the 
surfaces surrounded by the 
cutting edges. By means 
of open caissons founda- 
tions have been carried to 
a depth of 175 feet below 
water level — a truly remark- 
able feat, considering that 
the actual excavation is 
done by machines under the control of men a hundred 
feet or more above the surface attacked, who have to 




Fig. 88. — Sinking deep open cais- 
son by means of bucket-dredge 
operated from above the water- 
line. The shaded portions are 
chambers loaded with stones or 
concrete to force the cutting- 
edges downwards as excavation 
proceeds. 



142 



THE FOUNDATIONS OF A BRIDGE. 
IN II 111 



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1,1,1,1 



eS 



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ff^^VA 



1 1 .rjii 



111 



-r ,1 I I 



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S^^^MSMESSf^.^^^^^^ 



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y 



Fig. 89. — A masonry pier resting 
on piles. 



operate the dredges in 
sucli a manner ttiat tlie 
caisson, weighing per- 
haps several hundred 
tons, shall sink quite 
vertically. 

When the caisson has 
reached the required 
depth the dredges are 
renioved, and the open 
chambers are filled up 
with concrete, whereon 
the masonry of the pier 
is raised. 

COFFERDAMS 

are used where a good 
bearing material is 
found at a moderate 
depth. A cofferdam is 
generally constructed by 
driving a ring of piles in 
contact with one another 
round the area on which 
the foundations are to be 



THE FOUNDATIONS OF A BRIDGE. 143 

built, forming a second ring outside and parallel to 
the first, and filling the space between tbe two rings 
with claj. The enclosure is then pumped dry, the 
ground is excavated, the foundations are laid, and the 
pier is raised on them to above the outside water level. 
The cofferdam is then removed. 

In such cases it is common practice to sink piles of 
wood or metal down into the surface on which the 
foundations will stand (Fig. 89). The stability of a 
pile does not depend on the resistance of the ground 
to its point so much as on the friction against its sides. 
It is well known that though a pile may be driven 
quite easily provided that the blows follow at short 
intervals, it becomes immovable if driving cease for 
a considerable period. This is especially noticeable 
with piles driven into sand. 



Chapter VI. 
THE ERECTION OF A TRESTLE BRIDGE. 

Raising girders versus building out — The Britannia Bridge — The Gokteik 
Viaduct, Burma — Transporting the parts from Pennsylvania 
to Burma — Quick unloading— The beginning of the bridge — 
Lowering the parts into position — A tall tower — The value of 
organization. 

IE" the construction of long trusses of great weight, 
it is usual, where natural conditions permit, to 
build stout " falsework " platforms (see Fig. 84) up 
to the level of the pier heads, and on them assemble 
the members of the truss. This method is now gen- 
erally preferred to that of building the truss on the 
ground and raising it as a whole to its final position. 
Robert Stephenson was compelled by vexatious con- 
ditions laid upon him to resort to the second method 
for placing the tubular girders of the Britannia 
Bridge,^ and an anxious time of it he had while lift- 
ing the gigantic 1,500 ton, 460-foot, tubes from the 

* Across the Menai Straits. 



THE ERECTION OF A TRESTLE BRIDGE. 145 

surface of the Straits to their loftv seats 230 feet 
above, using extremely powerful hydraulic jacks for 
the purpose. The same may be said of Brunei, who 
raised the 1,200-ton bowstring girders of the Saltash 
Bridge 100 feet or more on to their piers. 

Where it is impossible , to erect falsework, trusses 
are sometimes built out on the cantilever principle, 
united in mid-air, and then cut into their destined 
parts over the piers. 

For lofty trestle bridges, such as are found in many 
parts of the United States, the cantilever " traveller " 
crane is largely employed. Such a crane starts at 
one end of the bridge, erects a column, lays girders 
from the abutment to the column, advances on to the 
girders, erects the next column, lays the next span; 
and so on till the bridge is completed. 

The Pennsylvania Steel Company, of Steelton, 
Pennsylvania, have been good enough to furnish me 
with excellent illustrations and a good account of the 
construction of a steel " trestle/' 

THE GOKTEIK VIADUCT, 

in the Shan States, Upper Burma. This viaduct 

forms part of the railway running from Mandalay to 
10 



THE ERECTION OF A TRESTLE BRIDGE. 147 

Kunlon on the frontier of Cliina. It crosses a deep, 
wide valley, its trestles being themselves supported 
by a natural bridge several hundred feet above the 
stream at the bottom of the gorge. The structure, 
2,260 feet long, has seven 60-foot plate-girder spans, 
and ten 120-foot lattice-girder spans, resting on skel- 
eton towers, the tallest of which is 320 feet high. 

All the metal parts were prepared in the United 
States, drilled for rivets and pins, assembled, discon- 
nected, and shipped to Rangoon, via the Straits of 
Gibraltar and the Suez Canal. Thence the Burma 
Railway took them to the scene of operations 460 
miles lip country. To use the words of the company's 
resident engineer, ^' The storage yard at the bridge 
head became a scene of mad activity. As the material 
came in from Mandalay, our big steam derricks 
whipped it out of the little, metric-gauge freight cars, 
and swung it over to the smaller derricks for final 
deposition, and coolies swarmed about with smaller 
pieces. The work went on with such speed that the 
engine-drivers and train hands could not shift empties 
in time to keep clear of the rush. So, when too many 
of them accumulated, we picked them up with the 
15-ton steam derrick, and set them down on the bank, 
where the drivers of the switching locomotives would 



THE ERECTION OF A TRESTLE BRIDGE. 149 

discover them, fifty feet below the level of the track, 
piled up like empty dry-goods boxes." 

The great ^' traveller " crane was then erected on 
the railway track at the south end of the bridge. It 
had a width of 24% feet, and an " overhang " of 165 
feet. The rear end was counter-weighted and could 
be anchored to the track to prevent any tipping up 
Avhen the cantilever arm carried heavy loads. Its 
general appearance and proportions will be gathered 
from rigs. 90 and 91. Fig. 90 shows it in course 
of erection, while in Fig. 91 it is seen engaged on the 
construction of a steel tower. 

As soon as it was in working shape, the materials 
for the first tower were taken to it in due order, 
lowered, and bolted in position, ready for the riveters, 
some 350 of whom were employed on the work. 
These quickly closed the rivets, and then '^ the big 
girders for the intervening space between the con- 
structed tower and the abutment on the bank were 
swung out; the longitudinal stringers and the cross 
floor beams followed ; ties and rails were laid for the 
trains with material, and tracks were laid on the 
girders for the traveller to run on. When everything 
had been completed, tackles were made fast to the 
traveller, and to the forward end of the girders, lines 



I50 THE ERECTION OF A TRESTLE BRIDGE. 

were carried to the winding engine, and the big 100- 
ton machine moved slowly forward to the edge of the 
newlj finished structure. There it was bolted doT\Ti 
in readiness for the next tower. To see it move ahead 
like a colossal drawbridge hundreds of feet in the air 
until the overhanging beams seemed on the point of 
toppling the whole mass into the gorge was a sight 
that the natives could never look on with equanimity.'^ 

Fig. 92 includes the highest tower of the viaduct, 
of nine stories of 35 feet each, braced in all directions. 
Below the third story from the top, the middle point 
of the transverse horizontal struts in each tower are 
supported by an intermediate central column. The 
central column is double, with six columns, which 
straddle apart 156% feet at the ground. The tops 
of the columns are connected by plate girders, 60 
inches deep, to carry the longitudinal girders support- 
ing the track and the ends of the span trusses. 

White workmen were employed on the " traveller " 
and on the topmost points of the rising towers, where 
the greatest skill and care were needed ; some of them 
nimble sailors who climbed the steelwork like cats and 
could keep a steady head at any elevation in ticklish 
places. Xine hours a day the men worked, except 
when the monsoon raged up the gorge or the sky 



THE ERECTION OF A TRESTLE BRIDGE. 151 

emptied itself in a tropical deluge. Pith helmets and 
thin khaki clothes were the only wear, with the sim 
blazing down hotly and almost vertically. But Old 
Sol didn't make much difference. Length after length 
of the column members were lowered from the trav- 
eller, outlined against the hard blue sky overhead, 
seized by ready hands, pinned into place, connected 
up with ties, and riveted, while the advance guard 
were already climbing to receive the materials for the 
next story. The coolies gaped to see the spidery 
structure rise at the rate of fifty feet a day. 

A tower completed, a truss, which had been riveted 
by the natives on the end of the bridge, was put on 
trucks and rolled forward under the traveller, picked 
up, moved slowly along under the projecting arm, and 
lowered on to its bearings. In some instances a girder 
was lowered in two parts which were riveted together 
in mid-air. 

So accurately had all the parts of the structure been 
made and fitted in Steelton that they went together 
again with no difficulty. The system of using dif- 
ferent colored paints to help distinguish the parts 
also promoted speed. Every week progress reports 
were telegraphed to the States, according to an elab- 
orate prearranged code which made it possible to 



THE ERECTION OF A TRESTLE BRIDGE. 153 

convey a lot of information in a very few words. 
Within nine months of the erection of the traveller 
crane the last dab of paint was put on the finished 
steelwork of the viaduct, and all was ready for laying 
the tracks. Five thousand tons of metal had been 
■placed ; some 200,000 rivets driven. 

The rails having been laid, the railway company 
tested the structure for two months under heavy loads, 
and expressed their entire satisfaction with the 
workmanship. 

At the time of its completion the Gokteik Viaduct 
was the second loftiest trestle bridge in the world, 
and for combination of height, length, and weight of 
material, easily first. So far as I am aware it has 
not yet been surpassed. Whether it has or not, it 
testifies to the development of the bridge-building art. 
Two hundred and thirty thousand odd pieces were 
shipped 10,599 miles in the confidence that they could 
all be assembled under strange conditions without a 
hitch ; and the faith justified itself. E'ot .a stick of 
staging had to be raised to help in the placing of the 
trusses, thanks to that excellent invention, the " trav- 
eller,'' which seems destined to find a wider and wider 
scope in engineering work. 

At present only one pair of rails has been laid over 



154 THE ERECTION OF A TRESTLE BRIDGE. 

the viaduct, but there is room for a second when the 
traffic requires a double track. 

The viaduct is- straight for 1,638 feet at the centre, 
and has terminal curves of 800 feet radius, and 341 
and 281 feet long respectively. 



i 



Chapter VH. 
SUSPENSION BRIDGES. 

The great suspension bridges over the East River, New York — The 
BrookljTn Bridge — Its dimensions and carrying capacity — The 
cables of a suspension bridge — Problems of their formation — 
Constructing temporary foot-bridges across the river — Spinning 
the cable wires — How it is done — Clamping and covering the 
cables — The Manhattan Suspension Bridge : 23,000 miles of wire 
— Facts and figures. 

A SINGLE square mile of the eartli's surface 
includes the three greatest suspension bridges 
in existence — the Brooklyn, the Manhattan, and the 
Williamsburgh, all of which span the East River, and 
form three of the great arteries of traffic between New 
York and Brooklyn. To be quite correct, the Man- 
hattan Bridge is at present only in course of con- 
struction, but its towers are up, and ere long its great 
cables and stiffening girder will dominate the ship- 
ping on the river, and we may therefore look forward 
a little and include it among present bridges. 

The Brooklyn • Bridge has been described so often 



156 SUSPENSION BRIDGES. 

that it will suffice to glance at the following facts 
and figures relating to it. It was begun in 1870, 
and opened for traffic in 1883. Its masonry towers 
rise 272 feet above, and reach 78 feet below, high 
water — 350 feet in all from rock to summit. Between 
them they consumed 85,000 cubic yards of masonry; 
and the two massive anchorages required as much 
again. The main span is one of 1,595% feet, and 
the two shore spans, from towers to anchorages, are 
930 feet long each. Add the approaches, and you get 
the total length of a mile and a furlong. 

The cables, four in number, each contain 5,296 
steel wires reaching from anchorage to anchorage, a 
distance of 3,572 feet. This gives a total of 14,000 
miles of wire. Each cable has a diameter of 15% 
inches, and a breaking strain of about 12,000 tons. 

The roadway, 85 feet wide, is divided into two 
carriage tracks, two street railway tracks, and one 
footway. The rise of the stiffening girder towards 
the centre of the span increases the headway between 
river and bridge from 119 feet at the towers to 135 
feet in mid channel. 

Vast as are the proportions of the Brooklyn Bridge, 
those of the Williamsburgh surpass them. This won- 
derful structure has a total length of a mile and 1,920 



SUSPENSION BRIDGES. 



157 



feet, including a main span of 1,600 feet and two 
shore spans of 600 feet. The four cables are each 19 
inches in diameter and built up of thirty-seven 
strands, each strand containing 208 wires, each 3,020 
feet long. Figure this out and you get 19,000 miles 
of wire; which, it may interest you to know, weighs 
5,000 tons. The wire used, by-the-bye, has a diam- 
eter of of an inch. 

Turning for a moment to the towers — steel in this 
case — ^we learn that they rise 335 feet above high 
water. The masonry anchorages to take the pull of 
the cables are of the most massive description, 150 
feet long, 150 feet broad, and 100 feet in height above 
the gTound. As for the stiffening girder, it is com- 
posed of two parallel lattice-work trusses, 67 feet apart 
and 40 feet deep — too deep for beauty, but necessarily 
so to stand without perceptible distortion the huge 
moving load to which it is subjected. The floor of 
the girder is extended 20 feet on each side outside the 
trusses. It gives accommodation for four street rail- 
way tracks, two elevated tracks, two eighteen foot 
roadways for vehicles, two passenger footpaths, and 
two cycle paths, so the bridge may therefore be con- 
sidered more roomy than any street in 'New York. 

Let us take the foundations of the towers, and the 



SUSPENSION BRIDGES 159 

towers themselves, and the ' anchorages for granted as 
built, since they afford no very striking features, 
apart from their huge dimensions, to delay us, and 
pass on to the consideration of the mighty cables 
which are the most interesting parts of a wire sus- 
pension bridge. 

The wires in such cables are not twisted like those 
of a rope, because twisting, though it serves to keep 
wires together, subjects them to different degrees of" 
strain. It is of the utmost importance that every 
wire in a suspension bridge cable should bear no more 
or no less than its fair share of the weight. This con- 
dition is fulfilled by forming the cables of parallel 
wires bound, not twisted, together. 

'Now, what was the task confronting the con- 
structors of the Williamsburgh cables ? First, to 
calculate the exact weight which the cables would have 
to support, the extent of their dip in the centre of 
the main span, their exact shape and position when 
finished; the tension on the cable due to its own 
Weight. These calculations must include due allow- 
ances for variations in temperature. Second, to make 
preparations for spinning 19,000 miles of wire across 
a busy waterway. Third, to form the cables and 
protect them from the weather. 



i6o SUSPENSION BRIDGES. 

In the auchorage at eacli end were embedded huge 
plates, and attached to these plates were large numbers 
of anchor chains made up of series of eye-bars* — 
four chains to every three strands in every cable. On 
the top of each tower rested four massive saddles of 
cast steel to carry the cables, mounted on rollers so 
that they might move a few feet in the direction of 
the axis of the cables, and ease the strain caused by 
variations of temperature and load on the bridge. 
Every wire would start from one anchor chain, rise 
to the top of the nearer tower, cross the river in a 
vertical curve, exactly regulated, to the further tower, 
and descend to its anchor chain on the other bank of 
the river. 

The mere placing of the saddles preparatory to 
spinning the wires required much calculation, as the 
attachment of the stiffening girder to the cables would 
draw the cables down in the central span, and cause 
the saddles to move on the towers. Any mistake 
could not be remedied when the cables were once in 
position. 

The saddles having been set, preparations were 

* An eye-bar is a long, flat bar of steel with expanded ends pierced 
by holes for the pins which connect the bars. The side plates of the 
links of a bicycle chain are eye-bars of very small dimensions, and 
the rivets represent the pins. (See Fig. 94.) 



SUSPENSION BRIDGES. 



i6i 



made for slinging a temporary light suspension bridge 
from anchorage to anchorage to afford the workmen 
easy access at all points to the cables during con- 
struction. The bridge had four footwalks — one for 
each cable — 3 feet below the imaginary line of the 




Fig. 9-i. — Transferring a -wire from the travelling sheave to its " shoe." 

cables during spinning. In the main span there was 
a lower deck of four footways similarly spaced from 
the line that the cables would take when the strands 
had all been formed and placed in their final positions 
on the saddles. 



i62 SUSPENSION BRIDGES. 



MAKING THE FOOTBRIDGE. 



The footbridge was supported by sixteen wire cables, 
2% inches in diameter, in four groups of three ropes 
each, and a single rope over each group. This is how 
a cable was slung. A tug took it, wound on a reel, 
to the foot of the !N"ew York tower, where it was trans- 
ferred to a lighter carrying a hoisting engine. A rope 
was passed from the lighter over a pulley on the 
tower and down again to the deck, and attached to 
the cable, 60 feet from one end. The loose end was 
lifted to the to]D of the tower, drawn by another 
engine back to the anchorage, and made fast. The 
floater then crossed to the other tower, paying out the 
cable, which sank to the bottom of the river. The 
400 feet remaining on the reel were now unwound 
and laid on the deck, and the end sent up the tower. 
On the Brooklyn shore stood a very powerful hoisting 
engine, which was connected up with the cable. All 
being in readiness for the final pull, joatrol boats 
stopped the traffic in both directions, and as soon as 
the stream was clear the hoisting engine started work. 
Slowly rose the cable, until its centre swung 150 
feet above the water, but it could not be made fast 
until adjusted to the exact deflection required as 



SUSPENSrON BRIDGES. 163 

ascertained by means of levels and transit instru- 
ments. So in turn all sixteen cables were treated ; 
and over them were laid planks to form continuous 
footAvajs, connected at short intervals by bridges. This 
part of the work was greatly facilitated by four trav- 
eller cranes, starting from the towers and working 
down towards the centre of the main span and to the 
anchorages. A general view of the bridge is given in 
Fig. 93. 

SPINI^ING THE WIRE. 

The next piece of business was to install machinery 
to carry the main cable wires across the river. This 
consisted chiefly of two endless travelling ropes, % 
inch in diameter, supported at intervals on pulleys 
attached to the footbridge, and driven by steam- 
engines with appropriate gearing stationed at the x^ew 
York end. The ropes ran from anchorage to anchor- 
age just above the line of the cables. It should bo 
explained that the one rope crossed the bridge over 
the first cable and returned over the second, while the 
other served the third and fourth cables in like man- 
ner. An elaborate installation of electric bells and 
telephones was a necessary adjunct of the ropes. 

The method of cable-forming used on the Williams- 



1 64 SUSPENSION BRIDGES. 

burgh Bridge is that invented in 1844 by Mr. John 
A. Roebling, and employed by him and his successors 
on the l^iagara, Cincinnati and Covington, and Brook- 
lyn bridges. It may be added that the John A. Roeb- 
ling's Sons Company was responsible for the cables 
now under consideration. 

What the method is may be understood easily with 
the help of Fig. 95. The thick dotted line represents 
one endless rope, carrying two sheaves, x and y^ sus- 

© A ---— -,^-^ (,)----rrr:._.- ^ ^^ 

Brooklyn I . , J J MfwfOI-li 

Fig. 95. — Diagram to explain the " spinning-in-the-air " method used to form 
suspension-bridge cables. 

pended from it by ^^ goosenecks " — iron bars curved 
to clear the supporting pulleys without hindrance. 

The sheaves are so spaced on the rope that when 
the one is at the Brooklyn anchorage the other is at 
the ]N^ew York anchorage. 

At each anchorage are two large reels of i\-inch 
wire, A, V), b^ c. The solid black semicircles, a, h, c, 
d, a/ 5/ c/ d,^ indicate the '^ shoes " roimd which the 
wires of four strands — two for cable 1, two for cable 
2 — will be wound. These shoes are attached to 



SUSPENSION BRIDGES. 165 

anchor chains, but not in their final positions, as 
adjustment will be required after the strands are 
complete. 

We will suppose that the workmen are about to 
commence stringing wires round a and a/ and h and 
1} Those on the E^ew York side unwind an end of 
wire from reel a^ attach it to shoe a, and pass a loop 
of it round sheave x. Simultaneously the Brooklyn 
party has attached the end of the wire at reel b to 
shoe h and formed a loop round sheave y. The signal 
is given and the rope begins to move, gradually extend- 
ing the loop on each sheave, and unwinding the reels. 
The side of a loop which is attached to the shoe is 
called the '' standing wire," and the reel side the 
" running wire," which travels twice as fast as the 
sheave. 

On completing the journey, the loop on sheave x is 
transferred to shoe a^ at the Brooklyn anchorage, and 
the loop on sheave y to shoe h^ at the 'New York anchor- 
age. Fig. 94 shows a sheave arriving and a workman 
attaching a tackle to the wire preparatory to its re- 
moval from the sheave. 

On the return journey the sheave x carries a loop 
from reel c, its end fixed to shoe c; and sheave y a 
loop from reel d, its end fixed to shoe d. Be it under- 



i66 SUSPENSION BRIDGES. 

stood that the direction of the rope's travel is reversed 
between every two journeys, sheave x plying back and 
forth over cable 1, and sheave y over cable 2. 

When the sheaves reach their original starting-point 
the new loops are transferred to shoes c^ and cl} 
respectively, and eight wires have been slung, and two 
strands begun in each of the cables. On alternate 
journeys sheave x draws put loops from reels a and 
c^ and sheave y draws out loops from reels b and d. 
During the construction of the Brooklyn Bridge cables 
only one reel was used for each cable, and the sheaves 
had to return empty one way. The stringing of those 
cables occupied twenty-one months; but the adoption 
of the double-ended method described above — and 
greater experience — reduced the period to seven 
months for the Williamsburgh Bridge. The maximum 
weight of wire slung in one day was lO^/o tons 
for the Brooklyn Bridge, and 75 tons for the 
Williamsburgh. 

Such, in brief, is the system of ^^ spinning in the 
air " invented by Mr. J. A. Roebling. 

Before the spinning could be actually commenced 
it was necessary to hang guide wires, of the same size 
and quality as those in the cables, two for each cable 
— since, as we have seen, tivo strands were formed by 



SUSPENSION BRIDGES. 



167 



each sheave. To make things quite clear to the reader, 
it should be explained that the wires passing round 
shoes a and a^ form one strand, those passing round 
shoes h and h^ a second strand, for cable 1 ; while 
shoes c c^, d d}, hold two strands for cable 2. 




Fig. 96. — A view of the strands of a cable. 

The guide wires were strung from anchorage to 
anchorage, and marked at points on the saddle. The 
length of wire between the saddles was the same for 
all strands, but that of the parts between saddles and 
anchorages varied, owing to the shoes being at different 
distances from the anchor plates. These variations 
were carefully allowed for. 



i68 SUSPENSION BRIDGES. 

The guide wires were transferred from the saddles 
to stationary sheaves at the side of the saddles in 
which the strands were formed. Up came the sheave 
carrying the first loop of a strand from the anchorage. 
When it reached the nearer tower, the standing wire 
of the loop was adjusted to hang parallel to the guide 
wire, and bound to it with twine at points 50 feet 
apart, and the running wire laid in pulleys on which 
it moved without friction. The adjustment completed, 
the men on the tower clamped the standing wire. The 
main span was similarly adjusted from the further 
tower and clamped, and the second land span from 
the other anchorage. The running wire was next 
adjusted in the reverse order, and the two first wires 
of the strand had been well and truly laid. This oper- 
ation having been repeated four times, the guide wire 
was removed from the saddle sheaves and laid aside 
until the commencement of the next strand. 

AVhen the travelling sheave had made 104 journeys 
the wire of the strand was disconnected from the reel 
feeding it, and the ends joined up. ]N^ow followed the 
operation of slacking off the strand at the anchorages 
till the shoes came into place bet^x^een their eye-bars 
on the anchor-chain, and could be finally pinned, and 
of lowering the strand from the saddle sheaves into its 



SUSPENSION BRIDGES. 



169 



final position on the saddle itself. These operations 
were accomplished by means of powerful screw 
apparatus. 

Thirtj-seven strands, arranged in a hexagonally 
shaped group, formed the cable, which had to be 
squeezed and bound with twelve turns of wire every 



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k 


li 


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i 


■|^:«^ii 


WrV t: \r^J- ' cl 


i^^WWB ^ '*-■: 




i 

^^■'"€1 




lIP^"" '^^X "^ 


.:M 


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mm 


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i'lG. 97. — Adjusting clamps to bind cable strands together. 

4 feet, and with large saddles for the suspenders of 
the stiffening truss. For the squeezing were used 
powerful steel bands tightened up by bolts and nuts. 
In Eig. 97 are seen some men at work with the 
squeezers. When the cable wires had been beaten with 
wooden mallets and constricted to the smallest possible 



I70 SUSPENSION BRIDGES. 

diameter, the Avire " serving " was applied close to 
the bands, and the latter were removed. 

To make all snug against the weather, the cables 
received a wrapping of Avaterproof material and an 
outside covering of sheets of thin steel. 

It is interesting to note that, though the work of 
cable stringing was necessarily of a very dangerous 
character, only one man lost his life — by falling from 
the footbridge into the river far below. 

THE MANHATTAN BRIDGE. 

Between the Williamsburgh and Brooklyn bridges 
the engineers are busy on the great Manhattan Bridge, 
which, though of less span than either of its neigh- 
bors, excels them both in its weight-bearing capacity. 

The original plans for this bridge specified eye-bar 
chains'^ to carry the stiffening girder, but it was 
finally decided to employ cables of unprecedented size. 
At the risk of wearying the reader I shall state that 
each of the cables contains 9,472 wires, and has a 
diameter of 21% inches. The total length of wire 
consumed will be 23,000 miles — almost sufficient to 
girdle the earth at the equator. As the wire used 
can withstand a pull of about 2% tons, each cable 

* Eye-bar chains were adopted for the Tower Bridge, London. 



i^i i ■ 



\: 1.1 




Fig. 97a. — A tower of the Manhattan Suspension Bridge. Each of the four 
legs measures 5 feet by 32 feet at the base, and rises 322 feet above the 
water. 

{Photo, " Tlie Scientific American. "''i 



172 SUSPENSION BRIDGES. 

would be able to suspend a couple of ironclads weigh- 
ing 12,000 tons eacb. The cables will be required, 
however, to endure the strain of but one-third of their 
breaking strain in the task of supporting a stiffening 
truss to carry eight railway tracks, two footpaths, and 
a roadway for vehicles. 

The total weight of the steel used in the bridge 
will exceed 40,000 tons, of which 13,000 tons will be 
absorbed by the great towers, whose tops are 332% 
feet above high-water level, and whose bases rest on 
great masses of masonry reaching down to the rock 
92 feet below high- water level. The total height of 
tower and foundation is therefore 424% feet — 
approximately the same height as that of the Forth 
Bridge towers and piers. Each of the anchorages 
measures 237 feet from north to south, and 182 feet 
from east to west, and rises 135 feet above ground. 
The weight of each, 233,000 tons, will easily resist 
the tremendous pull of the cables. 

One feature of the Manhattan Bridge that will 
distinguish it from its rivals is that the cables will 
not rest on movable saddles, but be permanently 
attached to the towers, which will bend slightly under 
variations of load. Another novelty is the employ- 
ment of nickel steel for the top and bottom chords of 



SUSPENSION BRIDGES. 173 

the four trusses of the stiffening girder, to save weight 
by its extra strength, as compared with ordinary steel. 

Note. — The photographic views illustrating this chapter were 
kindly supplied by Messrs. John A. Roebling and Sons, New York. 



Chapter VIII. 
CANTILEVER BRIDGES: THE FORTH BRIDGE. 

A glimpse of the Forth Bridge — The cantilevers — The towers — 
Skewbacks — Balancing the arms — Facts and figures — Prepara- 
tions for erection — Making the tube plates — Riveting — The ris- 
ing platforms — Adjusting the columns — The top chords — Build- 
ing the cantilever arms — Ticklish work — The suspended girders 
— Joining up— A delicate operation — An exciting incident. 

THE principles of the cantilever bridge have been 
explained on a previous page. It is now time 
to turn to an example or two of cantilever construction. 
There rises at once before the mind the huge Forth 
Bridge, which for years past has been the greatest of 
all cantilever structures, and will in some respects 
continue to be so even when the Blackwell's Island 
Bridge and the ill-fated Quebec Bridge are completed. 
Many accounts have been written of the building of 
the Forth Bri.dge, yet an apology is hardly needed for 
introducing the story of a great engineering triumph 
— the story of seven years of ceaseless and successful 
work, consummated on March 8, 1890, when, to tlie 



CANTILEVER BRIDGES. 



music of a gale raging through the 
criss-cross of steelwork, the (then) 
Prince of Wales declared the 
bridge open to traffic. 

Fig. 98 will help you to gain an 
idea of what the Forth Bridge 
looks like as seen from the flank. 
Let us imagine ourselves passen- 
gers on a boat passing up the Firth 
of Forth. For miles the great out- 
lines of the bridge dominate the 
landscape. As we approach, the 
estuary contracts to a width of 
about a mile and a quarter, be- 
tween E'orth Queensferry and 
South Queensferry; and soon we 
are almost under the bridge, and 
obliged to bend well back so that 
the eye may travel up to the top 
of the structure. 

Our guide takes up his tale. 
^' Ladies and gentlemen, it V\^ill 
interest you to learn that the rail- 
road track is 150 feet above high 
water. You observe that there 



8^ 






Kl- 



176 CANTILEVER BRIDGES. 

are six cantilever arms. Well, each of these is 
680 feet long, and the two suspended girders carried 
by four of them are 350 feet long; so that each of the 
two main spans, reckoned from tower to tower, is 
one of 1,710 feet — the greatest of all bridge spans. 
The towers ? Yes ! they are 342 feet from pier to 
summit, each consisting of four great tubes, 12 feet 
in diameter, built of plates riveted together. As you 
see, they are braced by other great diagonal tubes and 
by lattice girders, and though the columns appeared 
parallel as we approached, now that we are under the 
bridge you notice that they incline towards each other 
over the track. To be exact, the columns of each pair 
are 120 feet apart at the bottom and only 33 feet 
apart at the top. 

" The cantilever arms have straight upper chords 
of lattice form and tubular lower chords. The last 
are built up of tubes which have a diameter of 12 
feet at the bottom and gradually taper away towards 
their outward extremities. The upper and lower 
chords on each side are connected by six tubular struts 
and as many lattice ties, forming six bays, as 
the engineer terms them. Please notice that all 
^ members ' — the engineer again — that have to 
withstand compression are tubular in this bridge, 



CANTILEVER BRIDGES. 



177 



and those which are in tension are lattice-work 
girders. 

^' !N^ow consider the j)iers for a moment. They are 
twelve in nnmber, distributed in three groups of four 
among the towers. Tops, 19 feet above high water, 
and 45 feet in diameter. Best granite work on con- 
crete below-water foundations. To the upper surface 
of each a great bedplate is bolted do^vn — weighs 44 
tons; 5 inches thick. Another bedplate is attached 
to the bottom of the skewback of the column which 
it supports. The upper bedplate rests on the lower 
bedplate, and three out of the four upper plates for 
each tower are able to move a little over the under 
ones, to allow for expansion and contraction and 
varying wind pressure. ' Skewbacks ? ' They are the 
great junctions at the bottom of the columns, where 
^YQ tubular and '^yq lattice members meet. Yery 
complicated bits of work, eh ! I warrant Sir Ben- 
jamin Baker and his friends had to think about them 
a lot. 

^^ Are the end cantilevers out of balance ? E'o ; 
because the ends of the arms which rest on the 
masonry of the approach viaducts are loaded with 
dead weight equal to half that of the suspended 
girders carried by their fellow arms. Some one asked 



to 

12 



178 CANTILEVER BRIDGES. 

why the middle tower is so much longer than the 
others. You see, neither of its arms is supported, so 
it has to be made extra long to prevent any tendency 
to tip up if two trains happen to meet at the end of 
an arm. It is 260 feet long, as compared with the 
143 feet of the others. By-the-bye, wasn't it a lucky 
thing that the Inchgarvie rock happened to be in the 
middle of the channel? It saved the engineers a lot 
of trouble. 

" More facts and figures ? Well, the bridge, includ- 
ing its approaches, has a total length of 8,295 feet 9I/2 
inches. The superstructure contains 50,958 tons of 
steel, and required 6,500,000 rivets to fasten it to- 
gether. It's very strong, is the Forth Bridge. Sir 
Benjamin Baker told an audience that a battleship 
could be hung on the end of each cantilever arm with- 
out causing the ties at the tops of the towers to part. 
It may interest you, in conclusion, to be told that 
there are 145 acres of surface to be painted every 
three years." 

jN^ow let us throw ourselves back in imagination and 
watch 



CANTILEVER BRIDGES. 



179 



THE BUILDIXG OF THE EOETH BEIDGE. 

The soiitli shore of the firth has been terraced to 
accommodate shops and yards and a small town of 
houses for workmen. Special railways have been laid ; 







Fig. 99. 



-Diagram to show how the cantilever arms of the Forth Bridge were 
built out. 



telephones and telegraphs installed ; a water supply 
provided. Engineers have established the exact 
positions of the main circular piers by trigonomet^ 
rical calculations, and checked them with long wires 



i8o CANTILEVER BRIDGES. 

of a carefully measured length. The two north Fife 
tower piers have been built on the water-free rock, 
their southern fellows inside cofferdams. The Inch- 
garvie north piers also rise inside circular steel casings 
shaped to fit the rock below, and the two south Inch- 
garvie and all four South Queensferry piers have been 
built with the aid of pneumatic caissons after the 
manner described in a previous chapter. 

On shore men are busy preparing the great tubes 
of the bridge. The plates for these are shaped to the 
correct curve in rolling-mills, trued up in a hydraulic 
press, and passed through a great machine which drills 
rivet holes in them. As fast as they are prepared 
they are marked and transported to the piers, wdiere 
platforms and winding tackle are in readiness for the 
comm^encement of the superstructure. 

The skewbacks are already in place, and joined to 
one another by horizontal tubes and girders spanning 
the gaps between the piers. Upwards in many 
directions they send out the stumps of great members 
which will presently extend hundreds of feet into the 
air. 

Steam-derrick cranes lift plate after plate of the 
columns and hold them in place for the riveters. 
These plates jorove on close inspection to be half an 



CANTILEVER BRIDGES. i8i 

inch tliick. Every one is 16 feet long and 3 feet 
inches wide. Ten of them — five inside, five outside 
— riveted together by their longer sides form a length 
of tubing. The vertical joints are strengthened by 
girders of T section, the head riveted in with the 
joints, and every 8 feet is placed an internal circular 
diaphragm slotted at the circumference so as to pass 
the girders and reach the shell. These share with 
heavy plate girders, more widely spaced, the task of 
preserving the true circular form of the tubes. 

Allowing the hour hand of our mind-clock to reel 
off the weeks as if they were minutes, we see the 
columns rise to a height of 50 feet above the piers. 
The cranes cannot lift the plates any higher; so a 
second staging is constructed 38 feet above the first, 
and on this are built two pairs of great iron girders, 
each longer than the tower, running north and south 
in the line of the bridge and close to the columns. Let 
us call them the a girders. These rest on two cross 
girders, b^ pointing east and west, their ends project- 
ing through the columns, and below these are two 
beams, c, bearing on the columns. Hydraulic rams, 
resting on c^ support b^ which in turn support a^ on 
which are constructed platforms for cranes and work- 
men. Thus there are two platforms of about 25 feet 



l82 



CANTILEVER BRIDGES. 




Fig. 100. — The Fife Tower, Forth Bridge. Observe the rising platforms — sup- 
ported by cross girders projecting through the columns — and the riveting 
cages belove. 

(Photo by the late Sir Benjamin Baker.) 

wide and 200 feet long (350 feet long in the case of 
Inchgarvie) completely embracing and projecting some 



1 



CANTILEVER BRIDGES. 183 

distance bejond the vertical columns. As the towers 
rise they will ajDproach one another. 

Encircling the columns below the platforms are 
riveting cages, and inside the columns are correspond- 
ing cages, so that the riveting gangs may be drawn up 
after the platforms when the latter are raised. 

The hydraulic rams have a stroke of one foot. 
Everything being ready, those under one of the b 
girders are set to work. The girder rises a foot and 
is secured. The water is released from the ram, and 
the ram's support raised a foot. Then the other b 
girder is treated in the same way; and so on alter- 
nately till the platforms have risen 16 feet, the full 
height of a plate. 

Another course of plates is then built on with the 
help of the cranes, and meanwhile the men in the 
cages below add the plates omitted on the line of the 
B girders and complete the riveting. 

At intervals it is necessary to adjust the columns 
to the exact inward inclination required, forcing them 
apart with struts and rams till the line is correct. 
Simultaneously with the columns the main diagonal 
struts have progressed, and the diagonal cross ties 
under the railway track which will be. At the point 
where the struts cross one another some very intricate 



i84 ' CANTILEVER BRIDGES. 

work is done, consuming many tons of steel. Hori- 
zontal bracing is built in between the columns on 
one side of the central line and those on the other. 
Half-height has been reached. A large platform can 
now be built on which to store materials for the upper 
half of the tower. The riveters do not stop. Inside 
and outside the columns they work their hardest, 
squad vieing with squad. Every hour each machine 
closes its 80 to 90 rivets. 

At last the platforms reach their final position, and 
preparations are made for building the horizontal top 
ties for the columns. These are large lattice girders. 
The workmen first rivet up the bottom chords, then 
attach the lattice webs and add the top chords. As 
soon as the ties are self-supporting they are lifted 
from the platform on to the columns and made fast. 

The summit junctions next receive attention. Since 
they are almost as complex as the skewbacks, the 
assembling of all their members is not an easy 
matter, and to shelter the workmen engaged quite 
large three-story houses are erected 360 feet above the 
water. 

After the completion of the top work the travelling 
platforms are dismantled and transferred to the very 
summit of the towers. 



CANTILEVER BRIDGES. 185 

THE BUILDING OF THE CANTILEVERS. 

The work that follows is full of anxiety for the 
engineers, for it will put a much greater strain on 
the steelwork than heretofore. Refer to Fig. 99. 
This shows us two great travelling cranes, each 
weighing with its platform and gear some 64 tons, 
advancing into space along the top members of the 
cantilever arms, building them out as they move. The 
stress on these members — as yet entirely unsupported 
either vertically or laterally — means risk of disaster 
should a heavy gale blow up. From below rise the 
first compression struts and the lower chords — these ^ 
also unsupported — and the railway truss projects its 
ends far beyond the columns. Downwards the first 
ties are approaching the lower chords, to which they 
have already been connected by permanent vertical 
supports. 

At length the strut tops reach the upper chords; 
but before a junction is made the engineers check 
positions with their theodolites and, where necessary, 
raise the chords. Then the riveters become busy, and 
soon the first bay of the cantilever is secure, and the 
cranes may pursue their aerial journey. 



i86 



CANTILEVER BRIDGES. 



For eacli bay the same progress is repeated, tlie big 
cranes aloft feeding the workmen on the upper booms 
and the struts and ties in course of formation, while 
along the bottom chords advance riveting cages and 
cranes attached thereto. The amount of work pro- 
ceeding on the two cantilever arms is kept even, so 




Fig. 101. — General view of the partly-built cantilevers. 

that there may be no unnecessary strain on the col- 
umns. Each bay is shallower and narrower and lighter 
than its predecessor, and is erected more quickly. At 
the end of the sixth bay the arm is closed by a hollow 
box — 4% feet deep, 3 feet wide, and 40 feet high — 
open on the side facing the central girder. 



CANTILEVER BRIDGES. 187 

THE SUSPEJ^DED GIEDEKS. 

So lengthy a structure as the Forth Bridge must 
necessarily shrink or expand longitudinally to a 
marked degree as the heat of the atmosphere falls or 
rises. 

Due allowance for such changes is made at the 
points where the end cantilevers rest on the viaducts 
and at the points of junction between the Inchgarvie 
cantilevers and the two suspended girders. These last 
are also able to move slightly in a circular direction at 
both ends. 

The suspended girders were built out from both 
ends and connected at the middle, and the ends then 
released. The weight of the girder rests on its top 
chords, which, during erection, w^ere attached to the 
upper chords of the cantilevers by short tie plates. 
Between the bottom girder chords and the bottom of 
the cantilever end big wedges were driven in, so as 
to give the half girder a slightly upward inclination. 
This was needed in order to counteract the bending 
which took place as the halves were built out, and to 
bring the parts of the bottom chords into line. 

The travelling cranes already referred to were 
employed for the suspended girders, moving along 



i88 CANTILEVER BRIDGES. 

the top chords and hoisting np material from barges 
in the river. Eventually these cranes, which had 
started from the summits of the towers, met in pairs 
at the centre of the girders, and their work w^as done. 

!N'ow came the delicate and difficult work of joining 
up the girder halves. As the work had to be sup- 
ported by the temporary end ties until the junction 
had been made, it was necessary to effect the join in a 
temperature which would give the parts of the girders 
the exact length required. First the bottom chords 
were completed, the free ends being drawn together 
by hydraulic power and heat, and riveted to cover 
plates. There remained V-shaped gaps in the upper 
chords and webs, 10 inches across at the top and taper- 
ing downwards. Plates to fill these gaps exactly were 
made and attached to other plates which would be 
riveted to the upper chords. These plates and the 
upper chords were drilled ready for their rivets. 

The engineers had now to wait for the time when 
the temperature should fall to a certain point and 
widen the gap till the wedge plates could be inserted 
and fixed. Meanwhile furnaces were arranged round 
the tie plates to make them red hot when the moment 
for action should arrive, and ease their tension w^hile 
their rivets were removed. 



CANTILEVER BRIDGES. 189 

At last the gap opened siifficientlj. The wedge- 
pieces were inserted and the steel wedges between the 
cantilevers and the bottom of the girder drawn out, 
so as to bring all the weight of the girder on to the 
top chord and throw it into a state of compression. 
Men drove the rivets home, while others kindled the 
furnaces, and separated the ties, and at last the girder 
rode free, resting on its ends. 

At the closing of the northern girder a rather 
startling incident occurred. After the wedge-pieces 
had been inserted, and the workmen were cutting the 
ties, a sudden rise or fall of temperature took place, 
and the remaining bolts in the ties were shorn through 
and parted with a noise '^ like a shot from a 38-ton 
gun,'' as a witness describes it.^ The whole bridge 
shook from end to end, and some people feared that 
there had been disaster. As a matter of fact, nature 
had merely completed the work in a somewhat dra- 
matic manner.' 

The laying of the track calls for no special notice, 
though the bridge was to be the servant of the loco- 
motive. We may be sure, however, that it seemed a 
very easy and safe business after the many difficulties 

* Mr. W. Westhofen in "The Forth Bridge," to which fine account 
I am much indebted. 



iQO CANTILEVER BRIDGES. 

and hazards of the work that had preceded it. Of 
dangers there had indeed been plenty, and some dozens 
of men lost their lives during the seven years ; but the 
greatest bridge of its kind in the world, reared with- 
out setting a single stick into the river bed to support 
it, will for many years to come be their splendid 
memorial. 



Chapter IX. 
THE BLACKWELL'S ISLAND BRIDGE. 

The bridge — Its main features — Gigantic pins — How they put the 
bridge together — Huge stone supports — The island span — False- 
work — Twin travelling cranes — Making the arms — The capacity 
of the bridge — ^A huge arch bridge — Julius Csesar. 

THREE miles north of the Willi amsburgh Bridge 
there rises in the centre of the East River 
channel a long, narrow rock known as Blackwell's 
Island. This rock has served the same purpose as 
Inchgarvie, in the Eirth of Forth, for the engineers 
have utilized it to help support a huge cantilever 
bridge, which in a few years will unite Sixtieth Street^ 
Borough of Manhattan, with Ravenswood, Borough of 
Queens, on Long Island. 

In length and weight it rivals, in carrying capacity 
it surpasses, the Eorth Bridge itself. The trusses are 
the heaviest ever built. Fig. 102 shows this great 
structure in outline. It has six points of support — 
two terminal anchorages, and four piers — built on the 



192 



THE BLACKWELL'S ISLAND BRIDGE. 



f— ^ 



^•5 



firm rock through which the river 
has eaten out a channel. On the 
east and west edges of the island 
rise two of the piers, and the other 
two stand in line on the banks of 
the river. These piers support 
four cantilevers, which form two 
main river spans of 1,182 and 984: 
feet respectively, an island span of 
620 feet, and two shorter shore 
spans of 469% and 459 feet, mak- 
ing a total length for the bridge 
proper of 3,724% feet. 

FEATURES OF THE BRIDGE. 

This bridge differs from the 
Forth Bridge in that— (1) The 
members are j)inned together at 
points of intersection, not riveted. 
(2) It includes no suspended 
girders. In fact, the bridge is 
practically one continuous girder, 
with expansion joints at the centre 
of the river spans. (3) The truss 
members of the superstructure 



THE BLACKWELL'S ISLAND BRIDGE. 193 

were not built up bit bj bit near the site, but put to- 
gether by the manufacturers, the Pennsylvania Steel 
Co., and forwarded entire on cars or groups of cars, 
and pinned as the erection proceeded. 

A very pretty bit of pinning it has been, too. The 
things to be connected, great bars and girders, some 
weighing 120 tons each; the pins, cylinders of steel, 
some 16 inches in diameter and 10 feet long; the 
thimble, a 5-ton battering ram. And this pinning had 
to be done partly at a height of 300 feet above a deej), 
swift current, navigated by steamers, barges, ferries, 
and sailing ships, with the bitter winter winds raging 
furiously. 

The tension members of the bridge, the top chords 
and ties, are eye-bars arranged in groups, so that up- 
wards of twenty eyes would be threaded on one pin. 
You might think that for things so huge a close fit 
in the eyes and pins would not be necessary, yet the 
greatest allowance is -5^ of an inch. Much nickel 
steel was used in both bars and pins. 

HOW THEY PUT THE BRIDGE TOGETHER.^ 

The building of the piers was straightforward' work, 
as rock lies close to the surface of the gTound. For 
the piers great quantities of granite were shipped from 

13 




Fig. 103. — Blackwell's Island Bridge. Erecting tlie cantilevers. 
{Photo, ''Scientific American.'''') 




Fig. 104. — Assembling eye-bars. 
(Photo, "Scientific American") 



THE BLACKWELUS ISLAND BRIDGE. 



195 



Maine quarries, and dumped in specially built yards 
fitted with all kinds of ingenious machinery for shap- 
ing and handling the blocks. On the top of each pier 
are two huge stones to support the legs of the central 
^^ bents/' or legs of the cantilever. These stones 
measure 21% by 211/2 feet, and are enormously heavy, 
but they were raised 125 feet into position, set, and 
planed by special pneumatic machines till there were 
no variations greater than the thickness of a sheet of 
paper, and no hollows could be detected by the lev- 
elling rod. Then on them were laid massive pedestals, 
weighing 130 tons or so each, as footings for the 
bents. 

The island span (Fig. 105) was erected first to 
balance the nearer arms of the two river spans. In 
order to support the span during construction the engi- 
neers built an elaborate steel '^ falsework '' up to the 
level of the pedestals, and on it assembled the lower 
boom and a railway for two great travelling cranes, 
which hauled up and placed the members for the 
bottom half of the truss, including the tAvo decks which 
will carry the traffic of the bridge. 

The travellers worked from the ends of the span 
to the centre, closing their paths behind them, and 
were dismantled when their task was finished. 




Fig. 105. — The island span, showing falsework. Observe the two great 

" travellers." 

{Photo, Tfie Pennsylvania Steel Co.) 




Fig. 106. — Building out the arms from the island piers. The travellers have 

passed through the towers. 

{Photo, The Pennsylvania Steel Co.) 



THE BLACKWELUS ISLAND BRIDGE. 197 

Two Z-sbaped travellers, weighing 550 tons each, 
and having an overhang of 63 feet, were now erected 
rn the upper deck at the centre of the span. These 
had a sufficient height to dominate the truss at all 
points except near the bents. Moving away from one 
another they completed the truss, and passed through 
the bents, the cross bracings of which had been tem- 
porarily cut to give them passage. Then the jibs on 
their summits finished off the bents. During the 
process of pinning to the truss the bents were pulled 
inwards by extremely powerful hydraulic rams. 
December 4, 1906, saw the last pin of the central span 
driven into place. 

This done, the two travellers resumed their journey, 
moving outwards over the river, one towards Long 
Island, the other towards Manhattan (Fig. 106). As 
the river arms grew, the weight of the island span 
was counterbalanced, and it became possible to remove 
the falsework, starting from the piers, and use it 
to support the two shore arms. These were pieced 
together in much the same manner as the island span, 
and from them grew out the two remaining arms 
of the main river spans, which in due course gripped 
hands with the island cantilevers. 

The completed bridge will have a width of 88 feet. 




Fig. 



107. — Showing Queens anchorage and cantilever arms. 
(Photo, The Pennsylvania Steel Co.) 




Fig. 108. — ^Lower floor of island span and cantilever arms. 
(Photo, The Pennsylvania Steel Co) 



THE BLACKWELL'S ISLAND BRIDGE. 199 

On the lower deck, between the main trusses, 60 feet 
apart, there will be a central roadway 36 feet across, 
flanked at either side by a trolley track. Outside the 
trusses, supported on brackets, two more trolley tracks 
are provided for ; while on the upper deck we shall 
see four between-truss tracks, and two outside-truss 
footwalks, so that, as far as traffic capacity is con- 
cerned, the bridge may be reckoned a street 150 or 
more feet wide. When this steel-borne avenue is 
opened to the public the bridges lower down the river 
will not be quite so hard worked, as the districts near 
the ends of the bridge will draw off some of the pop- 
ulation from further south. Already there are schemes 
afloat for adding yet more bridges to the growing total, 
as !N'ew Yorkers are still unsatisfied. When the 
Brooklyn Bridge was the only alternative to the ferries 
the competition for seats in the cars that cross it was 
terrific at certain times of the day. The rising gen- 
eration of citizens may congratulate themselves that 
they have a larger choice. What will become of the 
ferry boats ? They will have to move off to other 
districts, where there is still room for them to be 
useful. 



THE BLACKWELL'S ISLAND BRIDGE. 201 



HELL GATE AECII BRIDGE. 

^^ Oh ! '' says the poor writer, compelled to say 
^' no " to many another bridge which clamors for 
mention, '^ there's a big number of you, I know — the 
Tower Bridge at London; and the ^N'iagara Suspen- 
sion, and the Niagara Cantilever; and the St. Louis 
Bridge ; and great bridges in India, Siberia, Germany, 
France. Yes, I know it; and I haven't forgotten the 
steel arch over the gorge down which the Zambesi 
thunders, below the Victoria Falls, and the three-mile 
bridge that the Tay glides beneath. I wish I had 
space for you all, but it's honest truth, I haven't." 

So it may seem unfair to look forward into the 
future, when the Pennsylvania Railroad Co. will 
bridge the East River at that spot known by the ill- 
omened name of Hell Gate with a mammoth steel 
arch to carry four railroad tracks. The plans for 
this bridge show a steel arch of 1,000 foot span — 
think of it ! — between abutments. These abutments 
— I now quote The Engineering Record — are monu- 
mental stone piles dividing the arch bridge proper 
from the steel viaduct that forms approaches to it. 
The tracks will be 140 feet above water, passing 



202 THE BLACKWELL'S ISLAND BRIDGE. 

through arches 130 feet higher. Some of the steel 
members will be 9 feet in maximum diameter and 
weigh a hundred tons. 

For the benefit of those who are interested in 
" records " I supply the information that this, the 
largest arch in the world (when it is completed) 
threatens to devour 80,000 tons of steel, enough to 
build four of the largest battleships. 

In concluding this chapter I conjure up the shade 
of that great general and old-time bridge-builder, 
Julius Caesar. He stands by the East River and gazes 
spellbound at structures which cross it. At his elbow 
is the modern engineer, who, modest man though he 
naturally be, cannot resist the temptation to borrow 
CsBsar's famous words, and mutter, '^ I came, I saw, 
I conquered.'' The shadow answers not a word, but, 
with the gesture of one vanquished, fades into 
invisibility. 



Chapter X. 
A TERRIBLE DISASTER. 

The Quebec Bridge — Its huge span — Measurements — Erection — An 
ominous occurrence — The fall of the structure — A tragedy. 

PASSING reference has been made to the Quebec 
Bridge, which will go doT\Ti to history as asso- 
ciated with a dreadful calamity. This bridge, of the 
cantilever type, was designed to span the St. Lawrence 
near Quebec, and link up the Canadian Pacific and 
Great Northern of Canada railway systems on the 
north with the Grand Trunk, Quebec Central, and 
inter-colonial systems on the south of the river. 

The most striking feature of the bridge was the 
great central span of 1,800 feet, made up of two canti- 
lever arms each 562% feet long, supporting a 675-foot 
centre girder. On the shore side of the towers two 
500-foot arms extended to abutments on the river 
banks, to which they were anchored. The towers, with 
summits 400 feet above the river, had but two col- 



204 



A TERRIBLE DISASTER. 



imins eachj resting on piers built at 
the edge of the water. The propor- 
tions of the structure will be gathered 
from the diagram Fig. 110. 

The plans were the three years' 
work of a very eminent American 
bridge engineer^ and had been care- 
fully checked many times to prevent 
mistakes creeping into the calcula- 
tions of the stresses which the various 
members would have to bear. The 
top chords of the cantilevers were 
made of great eye-bars, 76 feet long, 
15 inches deep, and from 1% to 2^4 
inches thick, joined by enormous pins 
of diameters varying from 1 foot to 2 
feet. For each of the bottom chords 
and main compression members two 
w^eb plates, 4:i/> feet deep, and braced 
together by a lattice of angle irons, 
were used — in decided contrast to the 
great tubular members of the Forth 
Bridge. 

The breadth of the roadway was 
to be 90 feet, to give room for two 



A TERRIBLE DISASTER. 



205 



railway tracks, two electric car tracks, and as many 
foot-walks and vehicle roads. 

In 1902 work commenced on the erection of the 
steel superstructure. The anchor and river arms of 
the south cantilevers went up in 1905 and 1906, a 
vast 750-ton gantry '^ traveller " being employed. 
With the building season of 1907 began the building 
out of the suspended girder from the finished canti- 
lever ; and by the last week of August about 200 feet 
had been put together, making, with the cantilever 
arm, a projection of 800 feet from the south pier. 

Then it was noticed that the bottom chord of the 
anchor arm was bending a little, and information was 
at once sent to the consulting engineer, but no orders 
came to clear the bridge of workmen till a thorough 
examination should have been made. 

On August 29, just before work had ceased for the 
day, and while eighty men were still at their posts, 
the whole structure rocked and fell with a crash, 
hurling the men into the river or burying them under 
its ruins. Between sixty and seventy lives were lost. 
In a few moments 15,000 tons of steelwork, the results 
of three years' labor, had been reduced to a tangled 
mass of wreckage, reaching far out into the river. 

Apart from the appalling nature of the human 



2o6 A TERRIBLE DISASThK. 

tragedy involved, the collapse of the structure spread 
dismay among bridge-builders of the continent. The 
plans were based on theories found unreliable in 
practice. Investigation of the ruins tended to prove 
that the compression chords, whose warping had been 
observed, were unequal to the strain put upon them, 
and that to their final crumpling up must be assigned 
the origin of the disaster. 

The Quebec Bridge will be built — of that we need 
have no doubt — ^but not before its design has been 
modified in several very important particulars. 



Chapter XI. 
THE DESIGNING OF DAMS. 

Great quantities of water wanted for towns, power, and irrigation — 
Storage necessary — The dam-builder's task — Classes of dams 
— Masonry dams — The earth dam — Some mathematical facts — 
Centres of gravity and pressure — Further considerations — Distri- 
bution of pressure — Sir Benjamin Baker's model — Summary. 

AMONG the most serious problems caused by the 
congregation of multitudes of human beings 
into great cities is that of providing these multitudes 
with an abundant supply of wholesome water, which 
is at least as necessary for their well-being as " the 
staff of life." Again, the advance of civilization de- 
mands more and more power to keep the innumerable 
wheels of industry moving, and no form of power is 
so cheap as that extracted from falling water. Once 
more, in many parts of the world the rainfall is so 
unequally distributed, both as regards its amount and 
the period during which it is precipitated, that only 
by storing the water when it is superabundant and 



2o8 THE DESIGNING OF DAMS. 

doling it out in the dry season can vast tracks of land 
be rendered fit for agriculture. 

Consequently the engineer has been compelled to 
exercise his noble craft in impounding water in vast 
quantities. His usual method is to select a valley 
through which flows a stream of sufficient volume to 
be valuable. In the winter it may be a roaring tor- 
rent, in summer a mere trickle ; but if its average flow 
is good, then it will serve. At a point where the sides 
of the valley close in and are steep he throws a dam 
across, against the upper side of which the imprisoned 
water piles up, until it reaches a height at which it is 
permitted to escape either over the dam itself or over 
a separate adjoining spillway. His task is beset with 
many difficulties, and is one requiring the greatest 
care, since the bursting of a dam is usually accom- 
panied by black tragedy. But because dams, especially 
those for conserving potable (drinkable) water, are 
often situated in comparatively remote places, they 
attract far less attention than other accomplishments 
of the engineer. ^^ The bridge across the I^iagara 
gorge, a mountain railway, a great ocean steamer car- 
rying thousands of tons of freight and moving under 
the influence of several thousand horse-power, more 
often fill our minds with thoughts of engineering 




Fig. 111. — Excavating foundations for the Bradford Supply Reservoir Dam. 



14 



2IO 



THE DESIGNING OF DAMS. 



triiim^Dli than the silent and forgotten dam, far np 
some rocky gorge or spanning some mighty river, 
storing up for our use an element necessary for onr 
very existence. ^N'one the less, however, is credit due 
to the man through whose intelligence such a work 
was conceived, and by whose skill and energy it was 
carried out."^ 

Cvcr'^-w Level 




Fig. 112. — Section of earth dam with concrete core. 



CLASSES OF DAMS. 

Large dams may be divided into two main classes 
— (1) earth dams; (2) masonry dams. A section of 
an earth dam is given in Fig. 112. It is essential 
that a dam, whatever its type, shall be impervious to 
water; and in this case the engineer puts his trust in 
a masonry core (marked black), which reaches down- 
wards to rock, to which it is firmly bonded. Being 

*Cassier's Magazine. 



THE DESIGNING OF DAMS. 211 

comparatively thirij it would be broken by the water 
if unsupported^ so on both sides are laid sloping heaps, 
the water face being protected by earth rammed down 
hard in layers, and puddled (rammed) clay — itself 
water resisting, provided it does not dry sufficiently 
to crack — and on the do^vn stream side by a bank of 
earth or gravel. The slopes of the embankment must 
be such that the materials used shall have no tendency 
to slip. The angle made by the face of the slope with 
a horizontal line must not be greater, than the '^ angle 
of stability " of the substance. If you pour sand 
slowly out of a bucket you will notice that the stuff 
forms a conical mound, which spreads in proportion 
to the increase in its height ; and try as you may, you 
cannot coax the sand to exceed a certain steepness of 
slope. Its ^^ angle of stability " is against you. We 
shall have something more to say on this subject when 
we come to discuss railway embankments and cuttings. 
A well-made earth dam with masonry core is 
staunch enough to be widely used for moderate 
heights. When a gi-eat depth of water has to be 
impounded the engineer prefers 

THE MASOiS'RY DAM. 

^ow, it may seem to you to be a very simple thing 



212 



THE DESIGNING OF DAMS. 



to build a wall across a vallev. '^ All you want is 
enough stones and mortar for the job." True, and 
not true. You certainly must have the right amount. 
The difficulty is to calculate this amount^ and to dis- 
pose it in such a form as to give you the best results 
for your money, and make everything quite safe. 

Let us examine the facts of the case, and try to get 

some definite ideas on the proportioning of a dam. 

You will have to think rather hard perhaps to follow 

me, but I will endeavor to be as simple as possible. 

First of all, let us consider the question of water 

pressure against a verti- 
cal face — say the side 
of a tank. The pres- 
sure increases with the 
depth. It is, speaking 
roughly, about 1 lb. to 
the square inch 2 feet 
below the surface of the 
water, 4 lbs. at 8 feet, 
and so on. If ab (Fig. 
113) represents the side 
of the tank, and we draw on ab a right-angled triangle 
ABC, having the side ab equal to the side bc, then that 
triangle will represent the total water pressure on ab. 




Fig. 113. — Diagram to show increase 
of water-pressure in proportion to 
depth. 



THE DESIGNING OF DAMS. 213 

In order to find what part of the pressure is borne by 
the upper half of ab a line, de, is drawn parallel to bc 
through T>, half way up. The quadrilateral dbce can 
be divided into three triangles, each equal in area to 
ADE^ therefore ad has to withstand only one-quarter 
of the total pressure. 

^ow let us go to actual figures. Assuming that 
AD is 1 foot high, the pressure would vary from nothing 
at A to % lb. to the square inch at d^ giving an average 
pressure of % 1^- ^0 the square inch. Taking db^ the 
pressure now increases from % lb. at d to 1 lb. at b^ 
with an average of % lb. to the square inch. So that 
it is evidently correct to represent the pressure by a 
triangle of the kind described above. 

We may now go a stej) further, and consider how 
we can best shape our dam to withstand a column of 
water pressing on one side. 

A wall, ABCD^ with both sides vertical, as in Fig. 
114, is perhaps most easily constructed. But since it 
is as thick at the top as at the bottom, whereas the 
water pressure increases steadily downwards, there 
seems to be a great waste of material somewhere. So 
we remove a part (1) from the top (Fig. 115) and 
place it at the bottom, to form a dam of triangular 
section bcd. This is more what w^e want, as the thick- 



214 



THE DESIGNING OF DAMS. 



ness of the dam increases downwards in direct pro- 
portion to the pressure that has to be withstood. 

CENTRES OF GRAVITY AND PRESSURE. 

So far we have been considering the tendency of 
water to thrust the dam horizontally in front of it. 







. .. 






^ ' •' c'-"''' 






/ir'-' "■'.■! '■'■' 


Outer 
Toe / 


<^': 


'■^■■■■■'■>:■^ 

■■ I-'.,",:'-; ;': 

-r.-. •■•■■.■-;■< 



c DC 

Figs. 114, 115. — Rectangular and triangular dams, showing transference Of 
position of part of the mass. 

This may be partly prevented by putting an obstruc- 
tion at "the ^^ toe '' c. But we shall not even so neces- 
sarily escape the danger of the dam being lifted behind 
and overturned on that toe. The question arises, 
Which is better fitted to withstand the overturning — 
the oblong section dam acdb (Fig. 114), or the trian- 
gular section dam bcd (Fig. 115) ? 

To answer this we must first think where the centre 
of gravity lies in each case. To find the centre of 
gravity of acdb we draw lines from a to d and from 



THE DESIGNING OF DAMS. 



215 



B to c ; and in the triangle bcd Ave join c and d to the 
centre of tlie sides opposite (Figs. 116 and 117). 
The points at which the two lines cut one another in 
A B B 



A;;s'Xr/ 




/ 






/■'X 






4-^0: 


:'',pS:yr 


-».p Cenfrp of /..:_ 
Pressure /.':■ '- 


'•■•>cg.,:. 


Y-y'i^k 


X'"'.'- " 


- ■; y . v:, 



Fig. 116, 117. — Showing how to And the centre of graTity of a rectangular 
and of a triangular dam. 

each case is the centre of gravity. E'ow^ neither acdb 
nor BCD will topple over when raised on one toe so 
long as the centre of gravity lies vertically over the 

B 





c c 

Fig. 118. — Dams tilted. The triangular dam has to be raised further than the 
rectangular dam for its centre of gravity to lie vertically outside the base- 
line. 

base. In Fig. 118 we see both raised almost to the 
toppling point. It is evident that the triangle gains 
stability by having its centre of gravity so far back 



2i6 THE DESIGNING OF DAMS. 

towards the water. The water has had to raise it 
much farther than acdb. 

With regard to the " centre of pressure '' mentioned 
in the heading of this section. The total pressure of 
water on a vertical face may be regarded as being 
concentrated into a single thrust on a point p, one-third 
of the way up the face, called the centre of pressure. 
This point is at the same level as the centre of gravity 
of the triangle bcd (Fig. 116), but below that of the 
oblong ACDB. So the triangle is once more seen to be 
the better form for a dam. 

I scarcely need, perhaps, to point out the reason 
for opposing the vertical face of the dam to the water. 
I have before me a w^ooden block of a section like 
that of BCD. After marking the faces bd^ bc^ one- 
third of the distance from the bottom, T apply the 
point of a pin to the marks in turn and push hori- 
zontally, while supporting the farther toe with the 
edge of a ruler, so that the block shall not slip bodily. 
I find that the pin penetrates the side bd more deeply 
than the side bc before the block begins to lift. 

FURTHER CONSIDERATIONS. 

The sectional shape of a dam is necessarily 
influenced by the nature of the materials of which 



THE DESIGNING OF DAMS. 217 

the dam is built ; but, speaking generally, its section 
is/ for the reason given above, roughly that of a right- 
angled triangle with the sloping face down stream. 
The water face has a slight '^ batter " or inward slope, 
in order to relieve the inner toe somewhat. See Fig. 
124, which shows a section of the famous new Cro- 
ton Dam, described in our next chapter. 




Fig. 119. — Diagram to illustrate the lifting-pressure of water. 

If given a chance, water will exert an upward as 
well as a horizontal thrust, and the overturning of a 
dam is made easier. 

Suppose that water penetrates under the masonry, 
as in Fig. 119; then the upward pressure on every 
square inch is that of the full depth of the water. To 
r3sort to figures. Supposing & c to equal d c, the 
pressure will be respectively proportional to a square 



2i8 THE DESIGNING OF DAMS. 

and a triangle — that is, the pressure on & c is double 
of that on d c. Also, it is exerted in a direction most 
dangerous to the stability of the dam. 

Hence engineers take the greatest pains to key the 
lowest foundation firmly to its bed/ and to prevent 
the formation of any horizontal cracks in the ma- 
sonry. 

The distribution of pressure on the base of the dam 
is not the same when the reservoir is full and when it 
is empty. In the second case the weight at various 
points is proportionate to the height of masonry above, 
and the engineer has to avoid the crushing of the 
foundation by putting too much weight on any one 
part. When the w^ater is at full height the centre 
of pressure in the dam is thrown forward towards 
the outer toe, and the engineer must be careful not 
to overload the foundations towards the toe. 

The late Sir Benjamin Baker illustrated the stresses 
in a dam by making a jelly model of dam and foun- 
dation rock, and drawing lines at right angles across 
its transverse section, to divide it into squares. 
Pressure being applied at the back to represent the 
water thrust, the yielding jelly became distorted, and 
the inner toe pulled the " rock " upwards while the 
forward toe pushed it down (Fig. 120). 



THE DESIGNING OF DAMS. 



219 



To sum up tliis chapter and set out the things which 
the builder of dams has to do: — 

1. To get a firm foundation. 

2. To bond the masonry to it in such a manner 
that it may not be pushed forward or admit water 
beneath it. 

3. To rear on the foundations a dam of such section 




Fig. 120. — Jelly model of dam distorted by pressure, to show stresses in a dam 
and its foundations. 

as best to resist overturning, while requiring the least 
quantity of masonry consistent with allowing a reason- 
able '^ factor of safety." The section has been shown 
to be roughly that of a right-angled triangle, with the 
right angle at the inner toe. 

I^ow we may allow ourselves a glimpse at the 
fashioning of some of the greatest dams that have as 
yet been erected. 



Chapter XII. 
THE BUILDING OF THE NEW CROTON DAM. 

The growth of New York's demand for water — The new dam; its 
great size — The Croton River — Plan of operations — Diversion 
canal — Removing debris — Cutting the foundations — Dam origi- 
nally partly an earth dam— Lajdng the masonry — Stopping springs 
—Work in cold weather — The earth dam; grave doubts about 
its safety — Its removal decided upon — The spillway — Clearing 
the reservoir area — "Pointing" the dam — The dam completed. 

MORE than sixty years ago the water supply of 
N^ew York proved insufficient for the needs 
of the population, and the Croton River, some thirty 
miles' distant, was laid under contribution. In 1843 
a dam was thrown across it a few miles above its con- 
fluence with the Hudson, and a lake was formed of 
2,000,000,000 gallons capacity. Subsequently the trib- 
utaries of the Croton River were dammed, one after 
another, to collect water that might be discharged into 
the lake when it became depleted. 

But still the needs of the city grew, and by 1890 the 
supply had fallen far short of the demand. It was 



BUILDING OF THE NEW CROTON DAM. 221 

therefore decided to build a dam some two and a half 
miles below the Old Croton, of such a height that the 
cubic contents of the lake should be increased sixteen- 
fold, and its depth be sufficient to completely sub- 
merge the original structure. 

The dam has a length of about 1,200 feet, and a 
maximum height of 300 feet from rock to crest. 
This makes it the highest dam in the world. It 
contains over 800,000 cubic yards of masonry, and 
so comes next to the Pyramids among masonry struc- 
tures. Its great bulk is due to the fact that, owing 
to the rock on which it is built being rotten, the foun- 
dations had to be carried in places to a depth of 130 
feet below the river bed — that is to say, more than 
tv7o-thirds of the entire mass are underground. 

The Croton River has an average flow of about 
15,000 cubic feet a second. Before any work could 
be done on the dam itself it was necessary to divert 
the stream through an artificial channel of sufficient 
size to pass the heaviest floods. Fig. 121 shows the 
plan of operations. A diversion canal, 1,000 feet 
long and 2,000 feet broad, was excavated in the rock 
of the right-hand bank, and strong retaining walls 
built, besides two large temporary dams reaching 
across the old course of the river, which is indicated 



222 BUILDING OF THE NEW CROTON DAM. 

in dotted lines. . Protected by the walls, the workmen 
began to excavate a huge trench with picks, spades, 
and steam shovels. The earth was removed to the 
adjacent spoil-banks at first by horses and locomo- 




FiG. 121. — General plan of operations, New Croton Dam. 

tives, then by stationary engines hauling laden trucks 
up inclined planes. When the slopes became too 
steep to render this method of transport economical, 
three cable ways, 2,000 feet long and 50 feet apart 
(Fig. 122), were slung across the valley parallel to 



BUILDING OF THE NEW C ROT ON DAM. 



223 



the axis of tlie dam, and nearly 300 feet above the 
lowest point of the excavation. Skips were run ont 
along these and lowered to the working parties, filled, 
raised, dra^vn over the spoil-banks, and tipped. Very 
slowly the vast open cut yawned wider and wider till 
it reached rock. This last varied so greatly in sound- 
ness that it was found necessary to cut do^vn very 
many feet further than had been allowed for in the 
original plans. The bed-rock contained numerous ver- 
tical fissures which could not be filled or left unfilled, 
for, as we have seen, leakage under a dam may have 
very serious results; and because every extra foot of 
depth to the dam meant an increase in width as well 
and a widening of the open cut, you will be able to 
understand that the actual cost of the dam far exceeded 
the first estimate. 

Referring to Fig. 121 for a moment, you will 
notice that the dam is apparently solid from end to 
end. As a matter of fact, at the point a there is a 
large arch, under which the water discharged over the 
spillway flows into the old river channel below the 
dam. Therefore the dam proper terminates at a 
towards the north. If the spillway built on to it be 
included, the total length of the mass is somewhat 
over 2,000 feet. I must now mention that the portion 



BUILDING OF THE NEW CROTON DAM. 22 



of the dam between b and c (about 570 feet long) 
was begun and partly completed as an embanked core 
dam of the type illustrated in Fig. 123. It was to 
be 30 feet wide at the top, with a slope of 1 in 2, 
giving it a base width of 650 feet. The core wall 
would be 6 feet wide at top, and increase to 18 feet 
at a point 136 feet lower, and thence have parallel 
sides to the bottom. It was intended to give it a max- 
imum height of 200 feet at its junction with the 




Fig. 123. — Section of the earthen portion of the New Croton Dam ; 
afterwards removed. 

masonry dam at the foot of the southern slope of the 
valley. We shall have more to say about this section 
of the dam a little further on. 

LAYI^^G THE MASOI^EY. 

During excavation the men encountered at founda- 
tion level caves in the rock, one of them measuring 
8 by 9 by 30 feet. These were built u]:) with rubble 
masonry, and cement was forced into any cracks that 

15 



226 BUILDIXG OF THE NEW CROTON DAM. 

might exist. Ruhhle masonry, be it understood, is 
masonry constructed of nnsqiiared stones, irregular in 
sliape and size, as opposed to ashlar, in Avhicli squared 
stone is used. It is customary to face rubble-work 
with ashlar, as the straight joints of the latter can be 
made staunch more easily. 

When a satisfactory foundation surface had been 
obtained, it was scraped with wire tools, roughened, 

Leve/ of \Natef 



Bed of Reservoir 


^^^^^^ ' 


Xi.;:.'.;' tirth':--:\\: 'j^^^^^H^ "-" ^^'"'"^ y^' 


^^[ /{"/"S ■.'■■■ ^^^^^^^^^' f'll'"S - yf^ 


X<> :: 


'fl^HpHHr' 




Jf/f^l^r Bed R ock 


" Fig. 124.— S 


sction of the New Croton Masonry Dam. 



washed scrupulously clean, and coated with best 
Portland cement. On this, the point of junction 
between nature's and man's work, no care was spared. 
You may picture to yourself the busy gangs, laboring 
in a pit protected from the river passing above them, 
preparing the great expanse of rock as thoroughly as 
a conscientious house-painter prepares the surface of 
a door or window frame before he applies his brush. 



BUILDING OF THE NEW CROTON DAM. 227 

For every stone, whether it scaled five tons or a 
hundredweight, a bed of mortar and concrete was pre- 
pared most thoroughly. All stones were laid convex 
face upwards, so that no air might be included. To 
ensure contact between bed and stone, the workmen 
raised and lowered the stone two, three, four, or more 
times until all hollows in the cement had been detect- 
ed and filled in. Spaces between the large stones were 
occupied by smaller stones set with similar care, so that 
no two stones should touch one another. Into every 
crack the men rammed cement with special tools. 

The work was expedited by great steel piles built 
into the masonry as it rose, and made to serve as the 
supports of derrick cranes. This method largely 
obviated the need for independent cranes, and was 
found so satisfactory that engineers will probably 
employ it on other structures of the same kind. 

At many points the men encountered springs, 
often of small volume, but in no case to be despised. 
They could be checked and rendered harmless in the 
following manner. Over the spring was built a 
masonry box, from which projected a vertical three- 
inch pipe. As the growing height of the masonry 
required, length was added to length, until the level 
was reached beyond which the water would naturally 



BUILDING OF THE NEW C ROT ON DAM. 229 

rise no further. Liquid cement was then forced into 
the pipe under great pressure to replace the water, 
which, being entirely excluded from the stone work, 
had to retreat to the place whence it had come. In 
this way water pressure between the courses (we 
noticed its dangers in the last chapter) was entirely 
prevented, so far as these springs were concerned. 

The work of building progressed in cold weather 
as well as in hot, for New York waited impatiently for 
an increased supply of water. Now, severe cold is 
one of the mason's enemies, as it plays havoc with his 
mortar if given the opportunity. Therefore, when the 
thermometer sank to freezing-point, all the sand used 
in the cement was piled over steam pipes to get thor- 
oughly warm before being mixed with water and tbe 
other ingredients ; the water itself had salt dissolved 
in it to lower its freezing temperature ; and the stones 
were heated thoroughly by playing on them with 
steam jets. At night the surface of the masonry had 
to be protected carefully with matting. 

THE EARTH DAM. 

Four years after the commencement of operations 
on the dam — that is, in 1896 — the aqueduct commis- 
sioners decided to extend the stone dam 110 feet fur- 



230 BUILDING OF THE NEW C ROT ON DAM. 

ther southwards than the plans allowed for. The 
balance amount of earth dam was proceeded with, and 
a large part of it completed by the spring of 1901, 
when some ominous cracks appeared in the core wall. 
The gentleman holding the post of chief engineer at 
this period conclnded, to use his own words,* ^^ that 
there was a fundamental weakness here, and there- 
fore it would be unsafe to proceed with the work. 
Close study brought to view objectionable points of the 
embankment and core Vv^all, the most conspicuous of 
which were three: First, the excessive height, narrow 
base, and unstable foundation of the embankment; 
second, the great height of the core wall; and, third, 
the double means afforded the water to reach the core 
wall." Enlarging on the first of these features, he 
points out that the Amawalk Dam, impounding one 
of the upper Croton reservoirs, while only 85 feet high, 
as compared with the 200 feet of the ^ew Croton, 
has an even wider base. With regard to the founda- 
tions of the embankment, it was a refilled pit (see 
Fig. 133), in which settlement would certainly occur 
sooner or later. Such a settlement must seriously 
imperil the core wall, to which, to make things worse, 
water would have access through the embankment 

* The Scientific American Supplement, August 13, 1904. 



BUILDING OF THE NEW C ROT ON DAM. 



231 



itself, and at the point of junction with the main dam. 
x\t this point it was absolutely impossible to keep 
water out, even if the embankment were thickened 
indefinitely. 

So the fiat went forth that the core wall must come 
down. It required some pluck on the part of the 
engineer to urge so drastic a course, but events proved 
that he was entirely justified in the position which 
he took up. For he tells us : '' In March, 1903, the 
core wall having been removed, it became apparent 
that the embankment and core wall would have been 
undermined and destroyed if completed under the 
original plan. The core wall was found to be resting 
upon limestone that in places was completely disin- 
tegrated to the form of loose sand, and other portions 
in the process of disintegrating were more or less hard, 
the softer part being in such a condition that it could 
be easily crushed by the hand to the form of sand, and 
would absorb water as freely as a sponge." One shud- 
ders to think of the possible consequences had the 
earth dam been allowed to remain. Imagine 32,000,- 
000,000 gallons suddenly let loose ! The history of 
dam-bursts makes sad reading, and had other counsels 
prevailed, the Croton Dam might have added a terrible 
chapter. 



232 BUILDING OF THE NEW C ROT ON DAM. 

However, down came the wall, and the thousands 
of tons of earth that had been dumped into the open 
cut on either side of it. The disappointed citizens of 
N^ew York were grievously vexed by the prospect of 
additional delay and a corresponding excess in the 
cost of the dam. But the engineers went right ahead, 
widened the foundations, and carried the masonry 

dam across to the south 
slope, in which it is firm- 
ly embedded. 

Simultaneously with 
the dam had risen the 
spillway shown section- 
ally in Eig. 126. It was 

Fig. 126. — Section of spillway, New 

oroton Dam. built of great granite 

blocks, some weighing 10 tons each, bolted to- 
gether by iron bars, so firmly embedded that it 
took a pull of 60 tons to dislodge some submitted 
to a test. The outer surface of the spillway is a series 
of steps, designed to break the fall of the water and 
protect the channel below. 

Early in 1905, when dam and spillway had reached 
a certain height, the diversion channel opening in the 
dam was quickly blocked, and the water allowed to 
rise till 1,000,000,000 gallons had been stored, cover- 




BUILDING OF THE NEW C ROT ON DAM. 233 

ing a wide expanse of hitherto unsubmerged country. 
The clearing of this area was a great work in itself, 
including the removal of three villages, numerous 
isolated buildings, cemeteries, farm premises, to say 
nothing of the transference of roads, railways, tele- 
graph lines, and bridges. In addition, 75 miles of 
stone wall had to be built round the area required 
for the reservoir. 

Since the water was more or less contaminated, it 
was drained away. The masons rigged up platforms to 
float against the upstream surface of the dam, so that 
as the water sank at a rate regulated to suit the work 
they might ^^ point " the masonry on the outside. 

After fifteen years of continuous labor, engaging 
upwards of 1,000 men, the dam was finished; and it 
now retains a body of water which assures a daily 
supply of 300,000,000 gallons to 'Bqv7 York. The 
lake behind the old Croton Dam was 6 miles long; 
the new lake is 19% miles from end to end, and so 
deep that when the water rises to its full height the 
old Croton Dam is submerged 34 feet. The new dam 
has a maximum height of 297 feet and a maximum 
width of 216 feet; it contains 833,000 cubic yards of 
masonry; required 1,500,000 cubic yards of excava- 
tion; and cost $7,500,000, a large part of the outlay 



234 BUILDING OF THE NEW C ROT ON DAM. 

being clue to the alterations in plan and the execu- 
tion of a vast amount of work which had to be un- 
done afterwards. From the financial point of view 
the structure was a very expensive one; as an engi- 
neering feat it is remarkable. The slopes just below 
the dam have been grassed down and laid out artis- 
tically and a fountain constructed to delight those who 
visit the spot ; and a power-house has been set up some 
distance below to convert the stored energy of some of 
the surplus water into useful electricity. 



Chapter XIII. 
HOW THE NILE WAS CURBED. 

The valley of the Nile — The Delta Barrage — A failure — British engi- 
neers to the rescue — Further schemes — A great survey — The 
Assyut Barrage — Sir Benjamin Baker's account — Diverting the 
main channel — The great dam at Aswan — Original plans — A 
straight dam decided upon — The course of operations — Forming 
sudds — Pumping out the water — Rapid construction — The lock 
gates — The sluice gates — Raising the dam. 

FROM a mountain stream we turn to one of tlie 
mightiest rivers of the world, the E"ile, the 
great benefactor of the Egyptian valley through 
which it flows. In Egypt water does not come from 
above as in most other countries, but rises from below 
— that is to say, there is no rainfall; and agriculture 
has in the past depended for its very existence on the 
yearly flood caused by the melting of the Abyssinian 
snow, when the river overflows its banks, and covers 
the lower parts of the valley, leaving behind it, as 
it subsides, a thick and rich alluvial deposit. This 
natural irrigation is replaced during the dry season 




m 



^^ 



HOW THE NILE WAS CURBED. 237 

b'^ artificial irrigation of a far less effective character, 
owing to the difficulty of raising large volumes of 
water to a sufficient height to be distributable over a 
wide area. In some years the 'Nile sinks so low that 
even the laborious raising of the precious liquid with 
the rude pole and bucket machine, which probably 
dates from the time of the Pharaohs, has to be 
controlled. 

Hardly a century ago, perennial irrigation was first 
attempted by cutting deep canals to convey water to 
the land at " low E'ile.'' Unfortunately these canals, 
inundated at " high ^ile,'' silted up and had to be 
cleared by the wretched fellahin at the cost of great 
cruelty and oppression. The system failed. 

There came to Egypt in the forties some French 
engineers, who said that the obvious thing to do was 
to save some of the flood's superabundance against the 
drought season by building a '^ barrage " across the 
Rosetta and Damietta branches of the ]^ile just below 
the apex of the Delta. A barrage, you must under- 
stand, is a weir or dam intended to raise the water 
level by but a few feet. The engineers accordingly 
constructed two long b'^'ick arch viaducts, containing 
132 large sluices, which were to be completely closed 
in the summer months, to head up the water some 



238 HOW THE NILE WAS CURBED. 

15 feet and throw it into the main irrigation canals 
below Cairo. Fifteen years elapsed between the com- 
mencement and the completion of the work, and when 
at last the engineer in charge closed the sluices the 
whole barrage began to slide down stream. Its foun- 
dations were insecure ! So the sluices were opened 
again hurriedly, and it was feared that a million 
sterling had been wasted. 

Presently English engineers appeared on the scene, 
examined the masonry, and issued reports to the 
Government. One report advised its entire removal; 
but Sir Colin Scott Moncrieff declared that he could 
underpin the foundations and make them quite firm 
for half a million sterling. His offer was accepted, 
and he carried out the work in the most masterly 
manner. At a later date subsidiary weirs were con- 
structed below the barrage to relieve it of some of the 
pressure by banking up the water downstream. The 
plan adopted for forming the weirs, and found suc- 
cessful, was to make contiguous solid blocks of masonry 
under water in a timber caisson that was moved across 
the river. 

The barrage greatly improved the irrigation of the 
Delta, but brought little relief to the higher reaches 
of the ISTile valley. Other constructions of the same 



HOW THE NILE WAS CURBED. 



239 



nature were so urgently needed that Lord Cromer 
commissioned Mr. William Willcocks to survey the 
whole valley, and ascertain the points at which the 
Mle could be dammed. Mr. Willcocks, accompanied 
by a faithful Nubian, tramped the country for three 









Fig, 128. — Water passing through the sluices of the Aswan Dam. 



years, at the end of which he drew up a long report, 
recommending a barrage at Assyut, 250 miles above 
Cairo, and a big dam at Aswan, 350 miles further 
upstream. His estimates of cost, however, were so 
high that for want of the necessary financial support 



240 HOW THE NILE WAS CURBED. 

the carefully executed plans had to be " pigeon- 
holed/' to await the day when they might be carried 
into execution. 

Luckily, soon afterwards, some capitalists and con- 
tractors expressed their willingness to invest money 
in the scheme, and to agree to repayment being spread 
over a long term of years. The contract for the bar- 
rage and dam fell to Sir John Aird and Co., who 
commenced work on both in 1898. 

THE ASSYUT BAEEAGE. 

!N'ear Assyut, the thriving capital of Upper Egypt, 
lying in a fertile plain at the foot of the Libyan 
Mountains, the N^ile contracts to a width of about 
half a mile. At this point a barrage, closely resem- 
bling that already described, was constructed in three 
and a half years — in a year less than the stipulated 
time. Its total length is 2,750 feet, or rath^er more 
than half a mile, and it includes 111 arched openings 
of 16 feet 4 inch span, which can be closed by steel 
sluice gates 16 feet high. Its purpose is to improve 
the present irrigation of Middle Egypt and the district 
called the Fayoum, and to bring about 300,000 more 
acres under cultivation by throwing water at a higher 



HOW THE NILE WAS CURBED. 241 




Fig. 129. — The upper illustration shows the closing of a sudd; the lower shows 
the water impounded by complete stone asd sand-bag sudd. 



242 HOW THE NILE WAS CURBED. 

level than formerly into the great Ibrahimyah Canal, 
whose intake is immediately above the barrage. 

The following is in substance the account cf this 
great undertaking as given briefly by the engineer 
responsible for its design, the late Sir Benjamin 
Baker, in a paper read before the Royal Institution 
of Great Britain. 

The piers and arches are founded upon a platform 
of masonry 87 feet wide and 10 feet thick, protected 
up and down stream by a continuous watertight line 
of cast-iron sheet piling, with cemented joints. This 
piling reaches down into the sand bed of the river to 
a depth of 23 feet below the upper surface of the 
floor, and thus cuts off the water and prevents the 
undermining which had given so much trouble in the 
case of the Cairo barrage. The floor is further pro- 
tected' along both edges by aprons of clay and gravel 
faced with stones. The roadway running along the 
crest is 41 feet above the platform, and each pier 
has an up-and-down-stream length of 51 feet. 

'' It is easy enough," wrote the author, " to con- 
struct dams and barrages on paper; but wherever 
water is concerned the real difliciilty and interest is in 
the practical execution of the works, for water never 
sleeps, but day and night is stealthily seeking to 



HOW THE NILE WAS CURBED. 



243 



defeat your plans. On the !N'ile the conditions were 
verj special, and in some respects advantageous. 
There is only one flood in the year, and within small 
limits the time of its occurrence can be foretold, and 
arrangements made accordingly. It would have been 
impossible to have carried out the E^ile works on the 
system adopted had the river been subject to frequent 
floods. The working season for below-water work on 
the ^ile lies practically between E'ovember and July, 
for nothing would be gained by starting the tem- 
porary enclosing embankments, or sudds, when the 
river was at a higher level than it is in ]N"ovember; 
nor Avould it be possible at any reasonable cost to 
prevent the sudds from being swept away by the flood 
in July. At Assyut the mode of procedure was to 
enclose the site of the proposed season's work by tem- 
porary dams or sudds of sandbags and earthwork, 
and then to jDump out and keep the water down by 
powerful centrifugal pumps, crowd on the men, exca- 
vate, drive the cast-iron sheet piling, build the masonry 
platform and piers, lay the aprons of clay and stones, 
and get the work some height above low ^ile level 
before the end of June, so that the temporary dams 
should not require reconstruction after being swept 
away by the flood. The busiest months were May 




Pig. 130o. — A lock in course of construction at the west end of ttie Nile Dam. 
Observe its great deptli. 




Fig. 130ft. — General vie\\ of the As\\;iii Ljui, showing water impounded 



HOPV THE NILE WAS CURBED. 



245 



and June; in the year 1900 the average daily number 
of men was 13,000. It is then also hottest, the shade 
temperature rising to 118 degrees. To keep the water 
down, seventeen 12-inch centrifugal pumps, throwing 
enough water for the supply of a city of two million 
inhabitants, had to be kept going, and in a single 
season as many as one and a half million sandbags 
were used in these temporary dams. The bed of the 
river being an extremely mobile sand, the constant 
work of the pumps occasionally drew away sand from 
under the adjoining completed portions of the founda- 
tions, necessitating the drilling of many holes through 
the 10-foot thick masonry platform, and filling under 
pressure with liquid cement. About 100 springs 
burst up through the sand, each one of which required 
special treatment." 

One of the most remarkable features of the work 
was the diversion of the channel of the river. For 
several years previously the main channel had shifted 
towards the eastern bank, leaving a large shoal on the 
vfestern bank. During the construction of the west 
part of the barrage the shoal helped the engineers, but 
when the eastern part had to be taken in hand it 
became necessary to alter the course of the main 
stream, which they effected by forming great embank- 



246 HOW THE NILE WAS CURBED. 

ments of huge stones from the east bank to the middle 
of the bed, so as to block the water on that side and 
compel it to scoop ont a path through the shoal. 

The barrage, which was completed in 1902, heads 
up the water to an extra depth of twelve feet. Just 
above the dam is the intake of the Ibrahimyah 
Canal, which follows the valley for a couple of 
hundred miles, and distributes water over many 
hundreds of thousands of acres. The Assyut 
structure is in fact the regulator of the water sent 
down from 

THE GREAT DAM OF ASWAN^ 

built across the First Cataract. This place was 
selected by Mr. Willcocks because the river here is 
bounded by granite hills and has a rocky bed in which 
firm foundations could be secured. The original plans 
of Mr. Willcocks allowed for a curved dam which 
could bank up the water to a depth of 120 feet, and 
form a lake of 3,700,000,000 cubic metres. But 
because such an increase in depth would submerge the 
fine ruins on the island of Philse, just above the site, 
it was decided to reduce the level to 67 feet, and the 
quantity impounded to about 1,200,000,000 cubic 



HOW THE NILE WAS CURBED. 247 

iHC'tres. For the curved dam was substituted a straight 
one, 11/4 miles long, containing 180 sluices, closed by 
gates of the Stoney roller pattern, easily raised even 
when subjected to a water pressure of several hundred 
tons. 

The task before the engineers was this: to build a 
great masonry mass, weighing some 500,000 tons, 
across channels through which the water rushes at a 
speed of 16 miles an hour with a turbulence almost, 
if not quite, equal to that of the Xiagara Rapids. 

The sketch map (Fig. 131) shows the five channels 
to which the flow of the river is confined at low Xile 
by the banks and rocky islands. Since the water 
must be allowed to escape at one place or another, 
it was impossible to block all these channels at once. 
So it was decided to attack the three easterly ^' babs " 
or " gates " — the Kebir, Haroun, and Soghair — first ; 
check the water here, lay the foundations*, then close 
the central channel, build across it, and finally dam 
the western channel after opening the eastern sluices 
in the partly finished dam. 

Sir John Aird and Co. signed the contract for the 
dam in February, 1898. By the end of two months 
the hitherto unpopulated desert had been transformed 
into a busy town, with works, offices, machine-shops, 



248 



HOW THE NILE WAS CURBED. 



hospital, and ac- 
commodation 
for 20,000 na- 
tives and Euro- 
peans. To the 
credit of the 
contractors b e 
it stated that 
they spared no 
expense to keep 
their employes 
healthy and 
comfortable. To 
takean in- 
stance: In view 
of the danger of 
sunstroke, tents 
were set np at 
many points, 
each containing 
a bath, ice-box, 
and a telephone. 
If a man snc- 
cumbed to the 
heat he was 




HOW THE NILE WAS CURBED. 249 

hastily placed in the nearest icecl-water bath to 
await the doctor who had already been sum- 
moned through the telephone. Consequently hardly 
a life was lost by sunstroke. What a contrast this 
treatment affords to the inhumanity that marred the 
making of the Alexandria Canal in the time of 
Mahomet Ali, seventy years earlier, when 20,000 
miserable fellahin, torn from their homes to do unpaid 
labor, died in the trenches ! 




:j Sandbag sSad C ^ff:-\ 



(Po^if'ion of 0am) 
(Space pumped dry) 



.'V>LLlJ_iLI i'-" lJ U IJ'_L|Ji' UIUULLUIU 
, /rM=>c=:^x=Lrz=y: Sandbag Sudd B ^=:' — "^^ cnj^J 

S V rn rnTTTi 1 1 ^^ r-rn ,-t ,-ri-n ^ in mr, 



1 . t 




Current 
Fig. 132. — Showing how a channel was closed by sudds. 

As at Assyut, construction could be carried on only 
imder the protection of sudds. But the raising of 
watertight sudds in the torrents of Aswan was an 
infinitely more difficult matter than it had been in 
the first case. In Fig. 132 is given a diagrammatic 



HOW THE NILE WAS CURBED. 251 

illustration of the manner in wliicli the engineers 
went to work. To check the water and produce a 
comparatively calm joool, stones weighing from 1 to 
12 tons each were flung into the stream, until a 
barrier, a^ 30 or more feet high had been formed 
above water level, heloio the line of the dam. The 
violence of the current was so great that the engineers 
had sometimes to fasten several of the largest stones 
together with steel wire, rope them to a truck, and 
send truck and all flying into the gap. AVhen a lodg- 
ment had once been obtained by these masses the com- 
pletion of the sudd was a comparatively easy matter. 

To fill the crevices between the stones large quan- 
tities of sand and cement were tipped on the up-stream 
side of the sudd. As soon as the barrier was staunch, 
a second sudd, b, of sandbags was formed above the 
line of the dam, and a second sandbag sudd below it. 
These last tw^o were placed in each channel after the 
floods of 1899. 

Early in 1900 began the exciting work of pump- 
ing out the spaces enclosed by the sudds and islands. 
The embankments proved to be so tight that the rock 
was soon exposed, and such leaks as existed were 
easily nullified by a couple of pumps to each channel. 
Then the workmen swarm.ed into the uncovered space, 



HOIV THE NILE WAS CURBED. 



253 



and with orderly haste cut awav all rotten rock, which 
in some places required excavating nearly 40 feet 
deeper than the level shown in the contract drawings, 
and increased the width of the foundations from 70 
to 100 feet. This was a serious set-back, since the 
masonry must be raised to above flood level before 
the next flood came. A thousand Europeans and ten 
times that number of natives were crowded on to the 
work, which for a month at least went on ceaselessly 
by night as well as by day, arc lamps giving light to 
the masons after sundo^^m. In one day as many as 
3,600 tons of masonry were placed, and with the great 
care required for work of this kind. The wiry 
Egyptians showed themselves no mean workers, and 
in a heat that was at times almost intolerable. 

When Father ^ile rose at the end of the year he 
was obliged to pass through a number of sluice-ways in 
the more than half -finished dam. E^ext year (1901) 
the western channel was closed, and work continued 
at the locks at the western end. The locks, four in 
number, are 270 feet long each, and 32 feet wide, 
and are provided with enormously strong gates which, 
instead of opening up-stream — as is usual — slide side- 
ways into recesses in the masonry, being suspended 
on drawbridges lowered when the gate has to be closed 



254 HOW THE NILE WAS CURBED. 

and raised when it is opened. At each end of the 
locks is a navigation channel cut in the rock of the 
bank to protect vessels from the strong current. Pre- 
vious to the building of the dam the services of some 
hundreds of men were required to get even a moder- 
ately sized vessel up through the Cataract. The 
largest river steamers are now able to pass it, and 
travel 800 miles further south, to Wady Haifa. 

In 1902 the dam was completed, and formally 
opened in December by the Duke of Connaught. Its 
maximum height is 130 feet, and its greatest (founda- 
tion) width — as we have already noticed — 100 feet, 
tapering to 24 feet at the top, where a roadway runs 
between parapets. 

Every year, when the river rises for the flood, all 
the sluices are opened, and the silt-laden water 
passes freely at the rate of 15,000 cubic metres per 
second. After the flood, as soon as the water becomes 
clear again, the sluices are closed gradually, and the 
water impounded imtil it is 67 feet deeper on the up- 
stream than on the down-stream face of the dam. 
During May, June, and July, the contents of the great 
lake, 150 miles long, are gradually doled out to the 
river below, and allowed to run down to Assyut, where 
it is directed into the irrigation canals. 



HOW THE NILE WAS CURBED. 



255 



THE SLUICE GATES. 



The success of the scheme depended largely on the 
ease with which the sluices could be opened and shut, 




Fig. 135. — Section of the Asvan Dam at a sluice 



therefore some notice is due to the sluice gates used 
in the Aswan Dam and Assyut Barrage. Because the 
silt suspended in the water is extremely valuable to 
the agriculturist, the ordinary spillway used in town- 
supply dams would not suit, as likely to cause the 



256 



HOW THE NILE WAS CURBED. 



silt to be deposited behind the dam, and so it was 
essential that there could be sluices controlled by gates 
opening upwards. The Stoney gate is a large iron 
shutter working up and down in strong steel sockets 
built into masonry. Between the vertical edges of the 
shutter and the down-stream jambs on wdiich they 
press are numbers of anti-friction rollers. (Fig. 




Fig. 136." — Diagram of Stoney sluice-gate, showing anti-friction rollers, a, 
and staunching-irous, b. 



136, A.) As these prevent close contact at these 
points the water would have a Avay through were it 
not for the long vertical staunching rods of angle iron, 
B, hanging freely by their upper ends. The pressure 
of the water forces them into the angle between the 
face of the shutter and the frame, and ensures a tight 
joint. So effective is the principle that two men can 



1 



HOW THE NILE WAS CURBED. 257 

raise and lower one of the sluices, against a pressure 
of 300 tons, with a simple crab winch. 



KAISING THE DAM. 

Though the clam has proved of incalculable value, 
its height is insufficient to store all the water that 
Lower Egypt needs ; in 1905 the reservoir w^as emptied 
completely and much land remained unirrigated. So 
in 1907 the work of raising the dam 23 feet and 
thickening it in proportion, to increase the storage 
two and a half times, was begun. The great difficulty 
that the engineers have to face is that of bonding the 
new and old masonry, as the old has cooled to a point 
which will not be reached by the new for some time to 
come. The extension will therefore be built as an 
independent mass, free to contract until it has the 
same temperature as the older work, and the two por- 
tions will then be joined by cement and steel rods. 

This addition will entail an outlay of about 
£1,000,000, and occupy the contractors for five years ; 
but to the credit side must be placed the reclamation 
of a million acres of desert capable of raising every 
year cotton crops worth some millions of pounds ster- 
ling. The Philse temples w^ill be submerged after all, 

17 



258 



HOW THE NILE WAS CURBED. 



and miicli as that fact is to be deplored, it is still more 
regrettable tliat the decision to snbmerge them was 
not made nine years earlier, before the engineers began 
Work at Aswan. 



[Note. — The photographic views illustrating this chapter were 
kindly supplied by Sir John Aird and Co., of London.] 



Chapter XIV. 
SOME NOTABLE RESERVOIRS. 

THE CATSKILL RESERVOIRS. 

The Catskill Reservoirs — Olive Bridge Dam. — The reservoir — Other 
great storage schemes — The Wachusett Reservoir for Boston — 
How Manchester, Liverpool, and Birmingham are supplied — ^An 
Australian dam — The Barren Jack scheme — An arch dam — Irri- 
gation projects — The Periyar, Tansa, Nira, Khadakvaria, Mara- 
kanave, and Dhukwa dams — Irrigation work dams in the United 
States — A Mexican dam. 

THOUGH the Croton River reservoirs discharge 
300,000,000 gallons a day into the aqueducts, 
the demand far exceeds the supply, and the ^ew York 
Water Board, foreseeing that the time is not far dis- 
tant when the enormous quantity of 1,000,000,000 
gallons will be needed daily, have taken steps to bring 
to the city an entirely new water supply, wdiolly inde- 
pendent of the resources of the famous Croton water- 
shed. 

About 80 miles E'.^.E. of ^ew York city lie the 
Catskill Mountains, abounding in splendid scenery 



SOME NOTABLE RESERVOIRS. 261 

and intersected by deep ravines running between 
almost perpendicular cliffs. Some 900 square miles 
of this region is to be drained into reservoirs having 
a capacity sufficient to give a constant supply of over 
600,000,000 gallons a day. Four streams will be 
impounded — the Esopus, the Rondout, the Schoharie, 
and the Catskill. 

Work has already been begun on the damming of 
the Esopus at a place named Olive Bridge, where a 
dam nearly 5,000 feet long and of a maximum height 
of 220 feet will, in conjunction with two miles o" 
dikes, enclose a lake 12 miles long and 2 miles wide, 
to be known as the Ashokan Reservoir. The lake will 
have four times the capacity of that formed by the 
:N"ew Croton Dam, and will contain 120,000,000,000 
gallons. 

As for the Olive Bridge Dam itself, it will be in 
three parts — a 1,000-foot central section of masonry, 
containing 1,000,000 cubic yards of masonry, and 
two end sections of core-wall earth dam, for which 
6,000,000 cubic yards of embankment will be re- 
quired; so that when completed, this huge mass will 
be the largest work of its kind in existence. An 
interesting feature of the masonry dam is a system 
of vertical expansion and contraction joints formed of 



262 SOME NOTABLE RESERVOIRS. 

stepped concrete blocks able to slide over one another, 
their faces being dressed with a compound to render 
the joints watertight while not hindering movement. 
It is expected that the cracking which usually results 
from the cooling of large bodies of masonry work may 
thus be entirely avoided. 

The reservoir is naturally divided (almost) into 
two basinSj one in the valley of the Esopus, and the 
other in that of the Beaver Kill, which flows into the 
Esopus just above the Olive Bridge Dam. A weir, 
2,200 feet long, partly of earth and partly of masonry, 
completes the division, and is of such height that 
water may pass from one basin to the other under 
certain conditions. 

Bound the limits of the Beaver Kill basin more 
than three miles of dike will be built; and for the 
overflow of the reservoir a 1,000-feet spillway is 
planned. 

A description of the aqueduct leading the water to 
the city of ^ew York is reserved for a later chapter. 

OTHER GREAT STORAGE SCHEMES. 

The Wachusett Beservoir, of 63,000,000,000 gal- 
lons capacity, and 6% miles area, was formed by 
impounding the Nashua Biver, in Worcester County, 



SOME NOTABLE RESERVOIRS. 263 

Massachusetts, by a dam 1,250 feet in length, 158 
feet high (maximum), and 120 feet thick (maxi- 
mum) . It ensures to the city of Boston a daily supply 
of about 100,000,000 gallons. 

The building of the dam was by no means the 
heaviest part of the work, for great dikes had to be 
constructed round the edge of the reservoir, and the 
whole of the area to be covered by the water cleared 



Oveffow Level of Water 




Fig. 138. — Section of earth dam, with clay puddle central wall, used for 
shallow reservoirs. 

of trees and buildings, and its surface stripped of 
earth to an average depth of 10% inches. The strip- 
ping alone cost $3,000,000, but the earth came in use- 
ful for the dikes referred to above. 

In England the cities of Manchester, Liverpool, and 
Birmingham draw the bulk of their water from dis- 
tant sources. 

To increase the Manchester supply a dam was 
thrown in the early eighties across the outlet of 
Thirlmere, a lake in Westmoreland, to raise the level 
of the lake 40 feet, and store over 8,000,000,000 gal- 



264 SOME NOTABLE RESERVOIRS. 

Ions of water. An aqnednct^ 96 miles long, connects 
Manchester with Thirlmere. 

The snccess of the enterprise stimulated the citizens 
of Liverpool to do likewise. A suitable collecting 
ground was found among the hills of E'orth Wales in 
the valley of Yyrnwy, a tributary of the Severn, which 
was closed by a dam 1,172 feet long, 161 feet high, 
and 127 feet thick at the base (maximum). Lake 
Vyrnwy, created by the dam, has an area of l-;^ 
square miles, and an average depth of about 70 feet. 
The dam, a fine piece of work, serves as a weir, over 
which all the surplus water falls. The supply is led 
to Liverpool through 69 miles of pipes, tunnels, and 
culverts, capable of passing 40,000,000 gallons daily. 

Birmingham draws its main supply from the head 
waters of the Wye, in Radnorshire, Wales. A series 
of danis have been constructed across the Elan valley, 
enclosing an equal number of reservoirs, which re- 
semble a flight of great water stairs, each level reach- 
ing to the foot of the dam above. Other dams will 
be added as required. The lowest dam, like tlic 
Yyrnwy, is a weir, and over it pours in flood time 
the finest waterfall in the kingdom. The Birmingham 
aqueduct ranks between the two already mentioned, 
being 74 miles long. 



I 



SOME NOTABLE RESERVOIRS. 265 

AN AUSTEALIAN DAM. 

The greatest river of Australia is the Murray, 
which drains the western slopes of the mountains of 
]!^ew South Wales. One of its confluents is called the 
Murrumbidgee. This river rises almost in the south- 
east corner of the state^ and about 150 miles from its 
source is swelled by the waters of the Yass and 
Goodradigbee. Like many — we might say most — 
Australian streams^ it varies greatly in volume at dif- 
ferent seasons. At times it overflows its banks and 
inundates the country far and wide, and at other times 
it almost disappears ; but on the average its flow is 
sufiicient to irrigate the great area of the desolate 
Riverina if its waters were stored. 

The Riverina includes much land which, given a 
reliable water supply, could be much more closely 
settled than is possible at present. The Public Works 
Department has therefore decided to dam the river at 
Barren Jack, three miles below the infall of the Good- 
radigbee, and impound the three streams so as to form 
a lake having an area of 20 square miles, and a capac- 
ity of over 33,000,000,000 cubic feet, practically equal 
to the reservoir ponded by the original Aswan dam. 

E'ature has been kind to the people of N"ew South 



266 SOME NOTABLE RESERVOIRS. 

Wales in one respect — she has at Barren Jack con- 
fined the river to a gorge, with granite cliffs rising 
to a height of 1,000 feet, and only 300 yards apart. 
Here there will be built a large dam of a type that 
we have not yet noticed. This is the arch type, in 
which the dam is curved, its convex side turned up- 
stream, so that the horizontal pressure of the water 
shall take the place of the vertical load on a bridge 
arch. As the thrust is transmitted to the abutments 
on which the ends of the dam rest (see Fig. 139), 
provided those abutments are very solid, a far smaller 
weight of masonry is required in an arch dam than 
in a straight dam. Consequently the arch dam is 
employed by preference in narrow gorges such as 
those in the Californian mountains, where several good 
examples may be seen — the most famous, the Sweet- 
water, 90 feet high and 340 feet long, " a narrow wall, 
bending upstream in a graceful curve, the slender out- 
lines of which cause a feeling of distrust in the non- 
technical observer as to its competency to perform the 
duty of holding back the waters of the river." * 

To return to the Barren Jack Dam. Its curve will 
be one with a radius of 940% feet, and the founda- 
tions are to have a maximum width of base (160-J 

* Cassier's Magazine. 



SOME NOTABLE RESERVOIRS. 



267 



feet) sufficient to allow the masonry to be raised to 
a final height of 232 feet from rock to crest. The 
length of the arc is about 900 feet. 

The structure will be of " cyclopean rubble " — that 
is, large blocks of granite set in cement. The rocks 



I I I 

I I I 

I ' i 
\Re6er\ioir 

1 1 / ; ' I ; 
1 1 1 1 1 ( I 





Fig. 139. — Arch Dam 



at the side provide an inexhaustible and convenient 
supply of materials (as was the case at Aswan), so 
the work will be carried through quickly. 

To let off the flood-water it is proposed to cut two 
large culverts through the cliffs round the ends of the 
dam itself, and as outlet, a 141/4 by 13 feet tunnel 



268 SOME NOTABLE RESERVOIRS. 

will be provided in the body of the main wall, con- 
trolled by valves worked from a separate masonry 
tower rising in the reservoir, and by a second set of 
valves near the down-stream face, operated from a 
chamber in the dam. 

When the work is finished, and the masonry wall 
connects Barren Jack with Black Andrew, the brother 
cliff on the other side of the gorge, the v\^ater will 
pond 40 miles up the Murrumbidgee, 13 miles np the 
Goodradigbee, and 19 miles up the Yass, and there 
will be in the heart of the mountains an inland sea 
on which all the navies of the world could float com- 
fortably. Flats will become broad lakes, and the hill- 
tops will stand out as islands. 

The water issuing from the reservoir is to pass 
down the existing river bed for 240 miles to ISTar- 
randera, .where is the off-take, or entrance, of a large 
canal, already partly excavated, that feeds a network 
of subsidiary irrigation canals. A million and a half 
acres will benefit, at a cost of an equal number of 
pounds to the Government ; and as Mr. Lee, the Min- 
ister for Public Works, aptly said, a district which 
has been described as ^^ l^o Man's Land " will be con- 
verted into ^^ Many Man's Land." That solitary dam 
promises to belie its name and to make a desert smile 



SOME NOTABLE RESERVOIRS. 269 

for a quarter of a million settlers ; and before many 
years have passed, it will be but one of a number built 
on the course of Australia's great rivers. 

OTHER GREAT IRRIGATION DAMS. 

Wherever there is an arid district occupied by a 
civilized people, and intersected by a river, there you 
will find schemes for water storage either completed, 
in course of completion, or planned for the future. 
It is impossible here to do more than briefly refer to 
some of the most notable projects which have not yet 
received our attention. 

India has always been noted for its great irrigation 
works. The Periyar Dam, in Travancore, ponds the 
river of the same name to form a huge lake, which 
is diverted by a tunnel cut through the watershed into 
the channel of the Valgai River on the other slope, 
and expends itself among the irrigation canals of 
Madura. Then there are the Tarsa Dam, Mysore, 
over 1% miles long, holding back a body of water 
larger than the Croton Lake ; the E'ira Dam, 3,000 
feet long; and the Khadakvasia Dam, Poona, 1 mile 
in length. To the Indian list will soon be added the 
Marakanave Dam, in Mysore, fit to rank in point of 
retaining capacity, v/ith the Aswan and Barren Jack 




^C^^3 




SOME NOTABLE RESERVOIRS. 271 

enterprises; and the Dhukwa Dam, Bombay. All 
these great structures protect vast tracts of naturally 
rich country from the miseries of periodical drought. 

In the United States great efforts are being made 
to reclaim the barren West; and every year sees 
thousands of acres of what was recently desert added 
to the agricultural area of the country. The Shoshone 
Kiver is being curbed in a canon by a dam 312 feet 
high ; the Yuma, by one 4,700 feet long and 346 wide, 
built safely on an earth foundation, ^or must we 
overlook the enormous Roosevelt Dam in Arizona, 
destined to create an artificial lake of unprecedented 
capacity, or the Pathfinder Dam, Wyoming, to im- 
pound 3,840,000,000 gallons. 

Mexico also is busy wresting land from the desert. 
Its most notable dam, the Jalpa, built a century ago, 
gave way during a fiood, and the water swept away 
everything, living and inanimate, that it encountered. 
Four hundred people were drowned. The stream 
hurled huge blocks of masonry hundreds of yards, 
rooted up the trees, and caused desolation where it 
passed. The dam has been rebuilt by the present owner 
of the Jalpa hacienda [farm], Mr. Oscar J. Braniff, 
and may claim to be the biggest thing of its kind 
erected by a single private individual. 



Chapter XV. 
AQUEDUCTS. 

Roman aqueducts — ^Their principle — The modern aqueduct — "Hy- 
draulic gradient" — Balancing reservoirs — Siphons — Pipe-joints — 
Notable aqueducts — The New Croton described — The Catskill 
Aqueduct — A colossal enterprise — Eho-mous siphons — The Cool- 
gardie pipe line — A novel kiad of pipe — Laying the pipe — Pump- 
ing the water — Charging the main — Wooden pipe lines — Some 
striking examples — A clever piece of work, shifting a pipe-line — 
A curious excavating machine. 

SOME of the most striking examples of ancient 
engineering which have survived the assaults of 
time are the aqueducts found in several European 
countries, Asia Minor, and E'orthern Africa. Most 
of them are the work of the Ecmans, who were as 
fully alive as we are to-day to the necessity of an 
abundant supply of fresh water for large to^\TL3. 

These aqueducts, some more than fifty miles in 
length, lead the water on a slight and unbroken 
gradient (Fig. 141) from source a to point of delivery 
B. As the Romans were unacquainted with the use 
of large metal pipes able to withstand high pressures 



AQUEDUCTS. 273 

they were obliged to bore through intervening moun- 
tains and bridge over valleys to maintain the correct 
decline required to carry the water at a certain speed. 
They naturally selected, as far as was possible, routes 
which avoided tunnelling and bridging; but when it 
became necessary to do either of these two kinds of 
engineering they showed themselves wonderful work- 
men, considering the rudeness of the tools and instru- 
ments with which they had to work. The ruins of 
the aqueduct bridges fill the beholder with admiration. 
I^ear Antioch, to take an example, is still to be seen 
such a bridge, 700 feet long and 200 feet high at the 
dee23est point. At Mayence are the ruins of an 
aqueduct over three miles long, carried on 500 to 600 
pillars. In many countries which the Romans once 
occupied you may see similar proofs of their con- 
structive skill. 

Though the bridgework formed so striking a feature 
of these old aqueducts, by far the greater part of the 
course was confined to stone and cement-lined channels 
cut in the earth and covered over. The perfect fit 
of the stones and the hardness of the cement-facing 
cannot be surpassed to-day. 

Bridge aqueducts are now confined for the most 

'part to canals, which must necessarily take a level 
18 



aqueducts: 

course between locks. The mod- 
ern engineer lias a great advan- 
tage over his predecessor of two 
thousand years ago in the large 
iron or steel pipes, which enable 
him to make use of the physical 
law that a fluid tends to find its 
own level, and will flow through 
a pipe of indefinite length, pro- 
vided that the exit be lower than 
the entry, no matter how many 
times and how far the pipe rises 



and falls in the intervals. 



pro- 



vided that it does not rise at any 
point above the altitude of the 
entry. (Under certain circum- 
stances even this last condition 
need not be fulfilled if the water 
be siphoned.) 



THE MODEEX AQUEDUCT. 

In Fig. 142 is sho^\ai dia- 
grammatically the course of an 
aqueduct of modern type run- 
ning over undulating country. 



AQUEDUCTS. 



275 



Totai_FaH 
' ' fi^ & £ 



rail 



^'\> 



The vertical heights are pur- 
posely greatly exaggerated pro- 
portionately to the length. 

A dotted line, running from 
the reservoir a to the point of 
delivery e, indicates the '^ hy- 
draulic gradient " or average 
rate of fall between the two ex- 
tremities of the aqueduct. All 
tunnels and masonry ducts are 
made to follow this gradient, so 
that water shall not flow faster 
at one place than at another and 
the pipe portions — that is, the 
siphons — also follow it in that 
the ends of each siphon lie on 
the gradient. (Please observe 
that these siphons are only so 
called for convenience' sake.) 
A real siphon takes Avater over 
a point higher than the surface 
of the source, the condition 
necessary being that the de- 
livery end shall be lower than 
the source. Siphons of the 



276 AQUEDUCTS. 

kind slioAvn in Fig. 142 are also named " inverted 
siphons '' to distinguish them. 

It is usual to divide an aqueduct which has a large 
total fall into several parts by '' balancing reservoirs '' 
B^ c, D. In Fig. 142 a horizontal line has been drawn 
at the level of the reservoir to a point over e to show 
the extent of the drop between these points. If a 
continuous closed pipe-line were used, the joressure 
at E might be excessive, and in event of an accident 
it would be difficult to execute repairs. If, however, 
the length be subdivided, as shown, the greatest 
pressure of anv one section, between a and b, b and c, 
c and J), D and e/ is dependent on the '^ head " of 
water in that section only. In our sketch the points 
of greatest pressure are obviously x and y, the lowest 
part of siphons 1 and 2, the '^ heads " being respect- 
ively the difference in the level of the reservoir b and 
of X, and of reservoir c and of ij. In the tunnel and 
cut-and-cover" portions (c-d^ and d-e), which follow 
the hydraulic gradient, the water runs freely and sets 
up but little pressure, though the masonry may be 
designed to withstand considerable stress. 



* By "cut and cover" is meant the method of scooping a trench in 
the ground and constructing in it a closed masonry duct, which is 
afterwards covered up witli earth. 



AQUEDUCTS. 277 

THE SIPHOIN'S. 

These parts of an aqueduct must be furnished with 
mechanism to minimize the effects of a burst, and to 
keep them clear of the silt which tends to collect at 
the lowest points. 

We may suppose siphon 1 to be twenty miles 'long, 
and made up of pipes of large diameter. If it burst 
at X, the escape of the water in the pipes alone would 
be a serious matter, to say nothing of that in the 
reservoir. 

It is obvious, therefore, that for safety's sake the 
engineers must provide automatic valves which shall 
close if the flow of water exceeds a certain pre- 
arranged velocity, as it would do in the case of a 
burst. In the lower leg of the siphon (that further 
from the source) ordinary flap valves opening only in 
the direction of the normal flow suffice, since the 
change of direction would here be sufficiently gradual 
to prevent any shock when a valve closed. In the 
upper leg, however, a valve of this kind would come 
into action with a suddenness that must burst the 
pipe. (On a domestic water supply connected with 
the town mains screw-down taps are compulsory, to 
prevent the flow being stopped too suddenly. ) So the 



278 



AQUEDUCTS. 



valves are of a different type — circular discs mounted 
on spindles projecting through the sides of the pipe, 
turned automatically across the bore by external 
mechanism to close the pipe gradually when the water- 
rush releases a trigger. 

For the cleaning out of siphons scouring valves are 
fitted at the lowest points. 

The pipes themselves are very carefully made, and 

tested with water at a 



Ica^ 




considerably greater 
pressure than they will 
have to withstand un- 
der ordinary condi- 
tions. Where an ordi- 
nary spigot and socket 
joint (Fig. 143) is 
used, the pipe is cast 
with the socket end 
downw^ards, so that the metal shall be densest at tlie 
part most liable to fracture. The joints are caulked 
by running molten lead in, and driving it tightly into 
place by hand or with special machinery, the shape 
of the socket giving the lead a very tight grip. Full 
particulars of every pipe are entered as it is laid, for 
future reference. Whether the pipes be placed above 



Socket 

Fig. 143. — Pipe-joint staunclietl witb 
lead. 



AQUEDUCTS. 279 

gTouncl or buried in trenches — in cold countries tliej 
are buried two feet or more deep to be beyond the 
reach of frost — they must be securely anchored to 
masonry or rock on the slo2:)es of hills and at curves, 
to prevent sliding in the one case and straightening 
in the other. The engineer is careful to keep all 
curves, whether vertical or horizontal, as gentle as 
possible. I may mention in passing that the Thirl- 
mere to Manchester aqueduct includes thirty siphons 
of various depth and length. 

NOTABLE AQUEDUCTS. 

We have already noticed briefly the pipe-lines con- 
necting Manchester, Liverpool, and Birmingham with 
reservoirs in distant hilly collecting grounds; but no 
mention has been made of the largest — as regards 
capacity — aqueduct in existence, the ISTew Croton. 
This delivers the waters stored in the Croton Eiver 
Valley by the dam described in a previous chapter 
and its auxiliaries to Xew York, 331/4 miles away. 
A remarkable feature of this aqueduct is the large 
proportion — 29% miles — '' in tunnel." Where the 
tunnels are under pressure (about 7 miles in all) they 
are of circular form, 121/4 feet in diameter; where 
not under pressure, the section is of horseshoe shape, 



28o AQUEDUCTS. 

13 feet 7 inches high and wide, Eor 2 -J miles eight 
rows of pipes, 4 feet in diameter, replace the tunnel, 
and the remaining mile is in " cut and cover." As 
the aqueduct approaches the Harlem River it falls on 
a steep gradient to the top of a vertical shaft 174 
feet deep and 12^/4 feet in diameter, down which it 
passes into a horizontal tunnel, 1,300 feet long, run- 
ning under the river. At the other end of this is a 
second vertical shaft 321 feet high, to allow the water 
to rise into the tunnel that carries it to the Jerome 
Park Eeservoir in the city of l^ew York. This is a 
good example of a masonry-lined siphon. 

The aqueduct is able to pass 300,000,000 gallons 
of water a day. It cost $20,000,000 to build, and 
ranks high among engineering feats. Of the tun- 
nelling work of the scheme there is no need to speak 
hero, as it properly belongs to a later chapter. 

THE CATSKILLS AQUEDUCT. 

The engineers are busy on another aqueduct which 
will presently bring the waters of the Ashokan Res- 
ervoir (described on pp. 260-262) to New York. The 
construction of this line is a colossal undertaking, for, 
apart from mere length — 82 miles — there are great 




Fig. 144. — Closing 30-inch locking-bar pipes in laydraulic press. 




Fig. 145. — Testing locking-bar pipes with high-pressure water. 
(Photos, 3Iessrs. Mephan Ferguson, Ltd.) 



282 AQUEDUCTS. 

physical difficulties to be overcome. The aqueduct 
has a diameter of about lY feet, and will convey 
500,000,000 gallons daily. This huge conduit will 
leave the reservoir in a deep trench, cross two rivers, 
and burrow a mile through the end of a mountain. 
After that it wdll run to the high ground on the north- 
erly side of the Rondout Valley. Here comes a great 
l^iece of engineering, the sinking of two shafts, each 
750 feet deep, and the driving of a tunnel 4% miles 
long to connect their bases. Progressing along the 
hill-side, it dives through the Shawangunk Mountains 
near Lake Mohonk, follows the Wallkill Valley for 
4 miles, drops down a shaft 480 feet deep, travels in 
a 4%-mile tunnel under a river, and rises through 
a second shaft. A. trench carries it toward the Hudson 
River, which it meets at Storm King Mountain. A 
third siphon will be needed to take it under this river. 
Owing to the great pressure in the siphons it is 
essential that the concrete lining should have a firm 
backing, and the engineers are therefore obliged to go 
do^vn to solid rock for the horizontal tunnel of each 
siphon. At Storm King the Hudson is more than 
half a mile wide and 90 feet deep. But the rock is 
far below the river bed, and it seems likely that the 
siphon here will have to be much more than 1,000 



AQUEDUCTS. 2^z 

feet deep, and able to stand a pressure of over 500 lbs. 
to tbe square incli. 

The aqueduct is destined, after crossing, to folloAV^ 
the left bank of the Hudson to the Croton River, under 
which it will burrow, and to run to a new storage 
reservoir 3% square miles in area, at Kensico, near 
White Plains, forming a two-months' reserve should 
the aqueduct have to be closed on the Ashokan side. 
After Kensico come the Scarsdale filter beds and the 
terminal distributing reservoir at Hill Yiew, in 
Yonkers, just north of the city boundary. 

The distribution of the water will be a big business 
in itself, as conduits must be carried from Hill Yiew 
under the East River near Hell Gate to supply the 
boroughs of Queens and Brooklyn. Another tunnel 
will make the passage of the Xarrows of Xew York 
Bay to Staten Island, where there will be a terminal 
reservoir 125 miles from the Ashokan Reservoir. 

This gigantic scheme will occupy the engineers for 
several years to come, and when it is finished it will 
far surpass in magnitude even the ]^ew Croton 
Aqueduct itself. 

THE COOLGAEDIE PIPE LIXE. 

So far we have been considering only " gravity " 
aqueducts, through which the water flows naturally 



284 AQUEDUCTS. 

by its own weiglit. The motive i^ower in such cases 
costs nothing at all. 

In Western Australia we find the most striking 
illustration of an aqueduct w^hich has its source at a 
much lower level than the towns which it supplies and 
which must have the water forced through it bv 
mechanical means. 

When the great inland goldfield of Coolgardie was 
discovered in 1892 the population of that part of 
the country began to increase at a rate that sorely 
perplexed the Government. The region is almost 
waterless, and scarcity of water (which rose in price 
to £4 per thousand gallons, and very bad water at 
that) for all purposes caused much distress and sick- 
ness among the population that flocked in to get its 
share of the gold. After much money had been 
wasted in sinking wells, it was decided to fetch a 
copious suj)ply to Kalgoorlie — 23 miles beyond Cool- 
gardie — from the mountains close to the western 
coast. This meant the laying down of 350 odd uiiles 
of steel pipes, 30 inches in diameter, to deliver 
5,000,000 gallons of water daily to the goldfields. 

A dam was thrown across the Helena River to 
impound a large reservoir, at a level of about 340 
feet above the sea. Xow, Coolgardie lies more than 



AQUEDUCTS. 



285 



f^'JSSPd'1 3'3'C.S'C . 




a thousand feet high, and on 
the farther side of ground 
which is higher stilL As 
water will not run uphill 
of its own accord, an elabo- 
rate system of pumping 
stations and receiving tanks 
was included in the scheme. 
A diagram (Fig. 140) 
shows the eight pumping 
stations, which raise the 
water in as many stages 
from Helena Reservoir 
to Bulla Bulling Main 
Service Reservoir, whence 
it flows by gravity to Cool- 
bardie and Kalo'oorlie. The 
approximate heights of the 
stations, of the receiving- 
tanks which feed them, and 
also of two regulating tanks 
between stations 2 and 3, 
are given in the sketch, as 
also the mileage of the in- 
tervening distances. 



286 



AQUEDUCTS. 



THE PIPES. 

After a series of careful tests, the Government 
adopted a novel form of pipe, invented by Mr. Meplian 
Fergusson, of Melbourne, and kno^^TL as the locking- 

M E PH A N - Fe RGUSONS 
Patent Rpvetless or Locking BarSteel Pipe. 




Cross Scction O FLE>.oTniwBLe. 

Fig. 147. — Details of locking-bar pipes. 
(Bij permission of Messrs. James Simpson and Co., Ltd.) 

bar pipe. A pipe consists of two plates of steel, each 
of the full length of the pipe and bent to a semi- 
circular form. The edges of the bars are beaded and 
inserted in long bars having a deep groove on either 



AQUEDUCTS. 287 

side, which are closed cold on to the plates by powerful 
hydraulic machinery. (See Figs. 144 and 147.) Each 
pipe is 28 feet long and % i^ich thick, and weighs 
11/2 tons. Before being passed it is subjected to an 
hydraulic pressure of 400 lbs. to the square inch. 
(Fig. 145.) Very few of the Coolgardie pipes leaked 
even to the extent of a few drops, so close was the 
joint. The finishing process was to dip the pipe into 
a bath of gas-tar and Trinidad asphalt, allow it to 
drain a minute, and revolve it quickly, so that the 
coating should be distributed evenly as it set. Some 
60,000 pij)es were required for the line. The con- 
venience of being able to import the parts, which 
packed into comparatively little space, and assemble 
them in the country, was a strong point in favor of 
this particular type, and no doubt led to its being 
chosen. 

Two factories were kept busy assembling the pipes, 
which were dispatched, as fast as closed, along the 
railway beside which the pipe line is laid throughout 
its course. Two trucks w^ould accommodate between 
them a stack of eight pij)es, loaded in eighty minutes 
and unloaded in an hour. 

Where they cross the salt-impregnated beds of 
former lakes the pipes are laid on trestles and covered 



288 AQUEDUCTS. 

over with sawdust packed between them and an 
exterior jacket of corrugated iron. Elsewhere they 
are buried in a trench, dug deep where the ground is 
loose (Fig. 148) or mounded over where it is hard 
(Fig. 149), so that they shall be protected from the 
heat and not require expansion joints. 

The work was divided into sections of about 14 
miles, each operated by a separate gang of men. 
When the works were in full swing seven gangs were 
engaged, and as the work to be done was the same 




Fig. 148. — Pipe in trench. Fig. 149. — Pipe in mound. 

throughout there was considerable rivalry among the 
parties. Careful supervision by inspectors, respon- 
sible for the quality of the work, ensured the mainte- 
nance of a high standard. " The rate of progress 
during the last three months, before approaching com- 
pletion caused disbanding, was, per day of eight work- 
ing hours of seven gangs. If miles of laying, jointing, 
and complete filling in of trenches. The appliances 
in use by each gang consisted of pipe-lowering trestles 
(see Fig. 150), four skids (one pipe expander, one 



AQUEDUCTS. 289 

lead melter and retainer, and the engine and caulking 
plant .... Foremost were the men repairing the coat- 
ing in the parts damaged during unloading or trans- 
portation, or where it had become defective owing to 
exposure for a considerable time to the intense summer 
heat; and in the same set were the pipe-scrapers and 
locking-bar chippers, who chipped or scraped off the 
coating at each end of the pipe for a distance of about 
6 inches, to insure good lead-running. IsText came 
men cutting manholes in the side of the trench opposite 
the joints a little ahead of those laying the pipes in 
the trench, and following these came the ring-setters, 
who wedged up the joint ring to such gauge as would 
give a lead joint of uniform thickness. In succession 
were the lead-runners, whose w^ork was, when possible, 
kept at least forty or fifty joints ahead of the caulking 
machine, especially in winter, as showery and cold 
weather affected the quality of the lead-running; thus 
stoppage in such weather, or defective work which had 
to be remedied, did not delay the caulking operations. 
Following on were the hand-caulkers, who caulked the 
joint at the locking-bar and for a distance of about 
four inches on each side of it ... . After the hand- 
caulkers came a machine, and as each joint was fin- 
ished the joint inspector examined it. Pipes were 
19 




Fig. 150. — Lowering pipes into trench, Coolgardie Pipe Line. 







Fig. 151. — Running lead into joints. 
(Photos, Messrs. James Simpson and Co., Ltd.) 



AQUEDUCTS. 291 

covered to a depth of at least 12 inclies as soon as the 
inspector had passed a joint and it had been tarred, 
so that the partial filling-in was only two or three 
joints at most behind the machine. The completion 
of the filling-in and the formation of the covering 
bank was always -100 yards or more behind the 
machine."* 

The caulking machine Avas constructed in two 
halves, to fit over and under the joints, the top half 
carrying an electric motor supplied with current 
through a cable, a quarter of a mile long, from a 
d}Tiamo worked by a portable oil-engine. A number 
of small rollers, working backwards and forwards 
round the pipe along each edge of the joint, pressed 
the lead home, and were then replaced by knives which 
cut it off neatly. 

THE PUMPS. 

The total vertical distance through which the water 
has to be lifted is 1,290 feet; and the frictional 
resistance of the pipes is equivalent to a further lift 
of 1,156 feet. Add certain other factors, and we find 
that the pumps have to overcome, in eight stages, a 

* "The Coolgardie AVater Supply," by C. S. R. Palmer. "Pro- 
ceedings of the Institution of Civil Engineers." 



292 AQUEDUCTS. 

pressure equal to that of water standing in a friction- 
less pipe rising vertically 2,635 feet. 

As 5,000,000 gallons have to be pumped daily, 
the machinery at the pumping station is of a very 
powerful and capacious kind. Twenty Worthington 
Pumps were installed by Messrs. James Simpson 
and Co., of ^ewark-on-Trent, England; three being 
assigned to each of the first four stations, and two to 
each of the last four. Great care was needed to avoid 
mistakes in j)acking, and to insure that every one of 
the twenty groups of machinery should arrive com- 
plete at its proper station. Each- group was therefore 
given a distinctive color and letter, and every part 
painted with the color of the group to which it be- 
longed. !N^o parts of different groups were allowed 
to be packed in the same case. As a result of these 
precautions only a single %-inch hydraulic valve was 
reported missing out of some 5,000 packages trans- 
jDorted from England to various points along the 
pipe-line. 

CIIARGIXG THE MAIX. 

In April, 1902, everything was ready for charging 
the main by filling the reservoirs and receiving tanks 
in succession. This was not so easy a matter as the 
reader may think. If air gets imprisoned in a siphon 



AQUEDUCTS. 293 

it may burst out, leaving a space into which the water 
rushes until it is filled. The sudden check then 
causes a '^ water hammer/' Avhich puts a great strain 
on the pipes and may burst them. A big main is 
charged slowly, and the air allow^ed to escape through 
valves provided for the purpose ; so you will under- 
stand why the water took eight months to reach Kal- 
goorlie at the end of the pipe-line. But ever since 
it did arrive the inhabitants of the goldfields have 
had a plentiful supply of good water drawn from a 
source as far distant in a direct line as London is 
from Berwick or Xew York from Lake Erie. The 
price of the water has now sunk to about two dollars 
per thousand gallons, less than one-twentieth of that 
of the condensed water on which the goldfields for- 
merly depended. 

WOODEN PIPE LIIs^ES. 

Where wood is plentiful and the country so rough 
as to make the transport of metal pipes a very 
difficult matter, wooden pipe-lines have been laid 
down, and have proved to be economical to manu- 
facture and cheap to maintain. 

On the Pacific Slope and in other parts of the 
United States some very large stave pipes are used to 




Fig. 152. — Tliree lines of 7-foot diameter wooded stave pipes. 




Fig. 153. — Forty-incb pipe on curve near San Diego, California. 

(Photos, The Excelsior Wooden Pipe Co.) 



AQUEDUCTS. 295 

supply towns or mining centres and irrigation works 
witli water. The wood most generally employed is 
that of the gigantic Californian redwood tree, well 
seasoned, and cnt np into staves, having the edges 
planed radially to the circle of which they will form 
part. The staves are held together at intervals — pro- 
portioned to the pressure of the water inside — hy steel 
bands tightened np hy a nut at one end screwed 
against a curved shoe attached to the other end. 

One of the largest stave aqueducts in existence is 
that supplying the city of Lpichburg, Virginia. It 
is 19 miles long, and the pipes are 30 inches in diam- 
eter. The construction was as follows. The wood 
came from California ready shaped, the staves meas- 
uring from 10 to 22 feet in length. These were 
assembled as quickly as possible, several gangs work- 
ing simultaneously at different points, and the trench 
in which the pipes lay filled in. To form a pipe of 
this kind a circular internal mould is used, which is 
moved along as the work proceeds. One side of each 
stave has a very small tongue along its centre, which 
digs into the flat side of the next stave when the bands 
are tightened and makes an absolutely watertight 
joint. The ends of the staves are kept staunch by the 
insertion of thin steel plates in saw cuts in the ends. 



296 



AQUEDUCTS. 



The plates, being a little wider than tlie staves, sink 
into the wood of the two adjacent staves and prevent 
any leakage. While the bands are drawn up they are 

r 




Fig. 154. — Building a -wooden pipe. Observe liow tlie staves " break joint." 

tapped with hammers to cause them to slip easily 
over the wood, and the pipe is '' coopered/' or beaten 
inside with mallets to make the staves lie snugly 
together. 



AQUEDUCTS. 297 

Provided that they are kept filled with water, 
wooden pipes are practically imperishable, so far as 
the wood is concerned. The metal bands and shoes 
will not last many years unless very carefully covered 
with some preservative against rust. 

This kind of pipe is made to withstand pressures 
ranging up to 90 lbs. to the square inch. For pressures 
above this figure metal pipes are used. Its cheapness 
is a great point in its favor. On the aqueduct men- 
tioned the amount saved by employing wood pipes 
instead of cast iron was estimated at $350,000 
(£70,000), which would enable the to^Mi after twenty 
years to lay a second wooden conduit of equal capacity, 
without spending more than iron pipes (interest on 
the money included) would have cost in the first 
instance. 

Denver is another city supplied through wooden 
pipe aqueducts, 30 and 34 miles in length respectively. 
Ogden, again, is fed by a vrooden conduit, in this 
case 72 inches iu diameter. 

A C LEVEE PIECE OE W^ORE!. 

You have doubtless heard or read of houses and 
other buildings being moved bodily from one site to 
another without interference with the occupants or 



298 AQUEDUCTS. 

injury to the structure. !N"ot long ago the engineers 
had to perform an even more difficult feat at Phila- 
delphia. This was to move 1,200 feet of 48-inch 
metal pipe 11 feet laterally and 13 feet vertically 
from its original position, and yet not stop the flow 
of the water, which was about 30,000,000 gallons a 
day. " Careful preparations were made for moving 
it into its new situation while under pressure. The 
centre line of the main in its original position was 
1.17 feet shorter than the calculated centre line for 
its new position. After it was moved careful meas- 
urements showed that the actual draw of the joints 
had only been 0.93 foot, or 0.21: foot less than was 
expected. This was very evenly distributed through- 
out the hundred joints, and the average movement of 
the pipe in each joint was slightly more than 0.11 
inch; In order to guard against excessive pull in the 
joints, each pipe was marked before being moved, on 
the top and on each side; but OAving to the fact that 
some of the pipes rotated 100 degrees, it was impos- 
sible to make proper reductions of the readings. . . . 
The trench for the pipe's new position was excavated 
to line and gradient; excavations were then made 
under the pipe on about 200-foot sections, and the 
pipe was lowered gradually to its new gradient, being 



AQUEDUCTS. 299 

meanwliile thoroughly braced in position to prevent 
lateral movement. After the pipe had been lowered 
to the new gradient, wooden skids, npon which iron 
strips were fastened, were placed beneath each length, 
and the pipe was then moved laterally into position 
with screw jacks. To facilitate moving the pipe the 
iron strips were kept well greased. The time occupied 
in moving the pipe was about one month, and except 
for a few hours, when a cracked pipe was discovered, 
the line was never taken out of service, and was under 
a uniform pressure of 70 lbs. per square inch. To 
avoid accidents and delays, rigid inspection was main- 
tained both bv nio-ht and dav, and men within easv 
hailing distance were placed along the line to ensure 
the immediate closing of the valves at either end in 
case of accident. After the pipe had been relocated it 
was allowed to rest for a few days until it had assumed 
its final position, and all joints were then thoroughly 
recaulked.""^ 

A CUEIOrS EXCAVATING MACHIXE. 

Fig. 155 is an illustration of a very queer-looking 
machine known as the Buckeye traction ditcher. As 
its name implies, its work' is to dig ditches or trenches 

* "Proceedings of the Institution of Civil Engineers.'.' 



300 



AQUEDUCTS. 



for water or drain pipes. The largest specimens can 
excavate a trench 4% feet wide and 12 feet deep at 
a rate which beats hand labor ont of the field. 

The apparatus consists of a platform carried on a 
pair of driving wheels and a pair of steering wheels, 
the latter broad like those of an ordinary traction 




Fig. i; 



•A Buckeye traciiou ditcher fur e^ 



engine. On the platform are a boiler and steam 
engine to operate the driving wheels and also the 
great circular digger, which is suspended from a 
couple of steel beams projecting from the rear. 

The excavating wheel has two rims set as far apart 
as the trench cut is wide. Between these rims are 



'AQUEDUCTS. 301 

attached a series of steel buckets, shaped somewhat 
like a coal-scuttle Avithoiit a bottom, and each rim 
is also furnished with a number of curved knives. 
The w^heel has no axle, but the rims, toothed inter- 
nally, run over cogs on the beams driven by the engine, 
and are kept from rising off these by an X-shaped 
framework fitted with large rollers that press on the 
inside of the rims. 

To start operations the wheel is set in motion and 
its supporting beams lowered gradually till it has 
eaten its way down to the full depth of the trench. 
Then the locomotive gear is brought into action, and 
the machine advances at any desired speed, scooping 
out the loam, clay, gravel, or even small boulders 
which it may encounter. As the buckets reach their 
highest j^oint they empty their contents on to an end- 
less belt, working at right angles to the direction of 
travel, which deposits the material in a long heap at 
one side of the trench. Owing to the absence of an 
axle the digger wheel can be sunk into the ground 
considerably more than half its diameter. By means 
of steering gear the line is kept straight or curved 
right and left; and where it is necessary to diminish 
or increase the depth on a regular gradient a sighting- 
bar mounted on the frame of the wheel is directed 







Fig. 15G. — A Buckeye ditcber at work. 



'AQUEDUCTS. 303 

on surveyor's ^^ flag-poles '' set up ahead, and kept on 
them by the operator, who raises or lowers the frame 
with a hand wheel and gear. The operator has perfect 
control over the depth to which the excavating wheel 
cuts, and he can keep the bottom of the trench within 
a fraction of an inch of the desired grade. 

The ditcher tackles any kind of ground that a man 
can excavate with a pick. It will eat through hard- 
pan, or shale, or frozen ground, and even the macadam 
road gives it no trouble. Should a buried log or 
timber get in its track it is chewed through, and a 
small iron pipe is treated in like manner. As for 
the actual feats performed by this wonderful machine, 
here is an example: 3,100 feet of trench 3.4 feet deep 
and 22 inches wide cut through clay in twenty hours. 
During a contest between men and machine, it took 
17 men and 3 teams ten hours to cut 900 feet of 
trench, while a Buckeye, operated by 3 men, cut 1,500 
feet. So you have all the facts for setting yourself 
a little proportional sum to show how much work a 
Buckeye man does in an hour as compared with a 
man using a pick. 



Chapter XVI. 
CANALS AND WATERWAYS. 

Canals to the front again— The advantages of canals — Two classes 
of canals — Boat-raising devices — The lock — Mechanical boat-lifts 
and inclines — Excavating operations — Dredges — Grabs — Steam 
shovels — Floating excavators — The bucket dredge — The suction 
dredge — Protecting the banks — A huge mattress — Ship canals — 
The Suez Canal — The Manchester Ship Canal — The Kaiser 
Wilhelm Canal — Some American schemes — A great Canadian 
project — Its significance. 

THERE be three things," wrote Lord Bacon, 
'^ which make a nation great and prosperous 
— a fertile soil, busy workshops, and easy conveyance 
for men and commodities from one place to another." 
Railway systems have been extended so enormously 
during the last three-quarters of a century that many 
people are unaware of the importance of canals and 
natural waterways as carriers of traffic. Yet for 
hundreds of years canals and rivers have been, and 
still are, in many parts of the world the chief means 
of transportation. The improvement of roads in the 
eighteenth century robbed many canals of a large part 



CANALS AND WATERWAYS. 305 

of their traffic, and the arrival of the railroad in the 
nineteenth put a number of once famous canals out 
of business altogether. At the present time, how- 
ever, there is a revulsion in favor of our neglected 
waterways, and many new canals of great length and 
size are being made at a cost which is sufficient proof 
that a need for them exists. Consider this, that on 
an ordinary good wagon road a single horse-power 
will draw about 3,000 lbs. at a rate of 2 miles an 
hour ; on a railway about 30,000 lbs. at the same rate ; 
on water as much as 200,000 lbs. Remember also 
that a boat will carry a much larger '' paying load " 
in proportion to its dead weight than can a cart or a 
railroad wagon. Therefore under certain conditions 
— namely, when a high speed is not essential, and 
the material to be moved is very bulky for its value 
— take grain and coal as examples — water transport 
has great advantages over rail transport. * 

For this reason the canal has, after a period of 
partial eclipse, come into prominence again, and given 
great opportunities to the hydraulic engineer for 
making artificial waterways where none such exist ; 
for canalizing rivers not naturally fitted for naviga- 
tion; for linking up navigable rivers; and, what is 

the grandest task of all, joining ocean to ocean by 
20 



CANALS AND WATERWAYS. 307 

channels deep and wide enough to carry the largest 
sea-going ships. " Hydraulic engineering has, next 
to railway engineering, been the most remarkable man- 
ifestation of applied science of modern times, and in 
canal construction it has attained some of its most 
successful results.""^' So no apology is needed for 
including in this book a chapter on canals, especially 
at a time when the progress of the mammoth Panama 
waterway is arousing world-wide interest. 

The subject is so large that we must here, as in 
connection with other branches of engineering, confine 
our attention to some general principles and a few 
notable examples. Canals in general may be divided 
into two great classes — (a) Those which require no 
locks or other means of raising boats from one level 
to another. These are comparatively rare, the most 
striking instance being the great Suez Canal joining 
the Mediterranean and the Red Seas, (h) Those which 
do require locks or other devices. 

BOAT-KAISING DEVICES. 

Water finds its own level. You can't grade it like a 
railway. Consequently every canal that has to be car- 
ried up and down hill must be broken up into steps or 

* S. R. Jeans in "Waterways and Water Transport," p. 15. 



3o8 



CANALS AND WATERWAYS. 



" reaches/' and some means found for transferring the 
boat or ship from one step to another. The most com- 
mon device is the loch, shown in vertical section and 
in plan in Fig. 158. It consists of a masonry cham- 
ber built at the junction of two reaches ; with a pair 
of gates, G G, at each end. It is filled by admitting 
water from the upper reach through sluices in the 



i/fiper Resch Leve/ 




Fig. 158. — Vertical section and plan of an ordinary lock. 

upper gates or in the side walls, and emptied by letting 
the water escape through sluices in the lower gates 
into the lower reach. There are usually two curved 
end extensions to the side walls to make entry into 
and exit from the lock more easy. The bottom of the 
chamber is a shallow inverted arch, which protects 
the ground below and also supports the side walls. 
At each end it terminates in a fiat portion called the 



CANALS AND WATERWAYS. 309 

gate floor, over Avliicli the gates move. Tlie gates 
themselves are, except in the case of the smallest locks, 
arranged in pairs, each gate being wider than half the 
width of the lock, so that when closed together the two 
form an angle pointing np-stream. The pressure of 
the water against their faces is transmitted to the 
pivots on which they hinge, and exerts a side thrust 
on the walls. Some gates are not straight, as in 
the illustration, but curved, so as to form a horizontal 
arch. 

In the walls are recesses, e -r, in which the gates 
lie when open, so as not to obstruct the passage-way. 

The operation of a lock is as follows. One or other 
pair of gates is always kept shut. In Fig. 158 the 
water inside the lock is at the level of the lower reach. 
On the approach of a boat travelling up-stream, the 
lower gates are opened, the boat admitted, the gates 
and lower sluices closed, and water let in from the 
upper reach until it raises the level inside the lock 
to that of the upper reach. The upj)er gates are then 
opened, and the boat floats out. If a boat w^ere now 
to be passed in the opposite direction, it would be 
locked, and when all the gates had been shut the lock- 
man would release the water through the lower sluices 
till it sank to the level of the lower reach. 



3IO CANALS AND WATERWAYS. 

In the event of the lock-level being " against " a 
boat, the water is rim off or let in, as the case may 
need, to equalize the lock-level with that of the reach 
in which the boat is. 

The nsnal lift of a lock is from 3 to 12 feet, but 
this is far exceeded in some instances. The Panama 
Canal locks will have a lift of 31 feet or more. 



Fig. 159. — Flight of contiguous locks. Tbe clotted area 
in each signifies the vrater that must be admitted to 
float a boat iuto the lock above. 



Where the rise of the canal is very rapid, it is 
necessary to have a '' flight " of several contiguous 
locks, the lower pair of gates of one lock acting as 
the upper pair of the lock below. In Fig. 159 we 
see a flight of five locks. The solid black portions 
indicate the water at its low level for receiving a boat 
from a lower lock, and the shaded portions the water 
that must be admitted to pass a boat up-stream. On 
canals where the traffic is great it is sometimes found 




Fig. 100. — River vrith falls canalized. The lower sketch shows locks, towing- 
paths, backwaters, and weirs. 



312 CANALS AND WATERWAYS. 

expedient to duplicate the flights, the one line being 
reserved for " np " and the other for " down " boats. 
The size of the locks on a canal are generally jnst 
sufficient to accommodate the largest vessels that ply 
on the canal. At present the largest lock in existence 
is one on the '^ Soo " Canal, connecting Lakes Superior 
and Huron. The Poe lock, as it is named after the 
engineer who designed it, is 800 feet long, 100 feet 
wide, and 21 feet deep. The side walls, including 
the parts outside the locks, have a total length of 
1,100 feet and a maximum thickness at the bottom 
of 20 feet. Five great steel gates let the water in and 
out. A single gate w^eighs 190 tons. This huge 
lock, built at a cost of $5,000,000, will be eclipsed by 
those on the Panama Canal, which, in view of the 
increasing size of ships, will have a width of 110 feet, 
a length of 1,000 feet, and a clear depth of 45 feet 
over the sills. 

MECHA]S"ICAL BOAT-LIFTS. 

A second method of raising boats from one level 
to another is the lift. In Pig. 161 we give a simple 
sketch of the general principle of a hydraulic lift. 
Two tanks are mounted on the tops of two very large 



CANALS AND WATERWAYS. 



313 



hydraulic rams having a stroke equal to the difference 
in level of the two reaches. The ram cylinders are 
connected by a pipe. When one ram is at the top 
of its stroke the other is fully down. If the tanks 
are filled equally, each exactly counterbalances the 
In the sketch two barges are about to be trans- 



other, 
ferred. 



Tank a is not filled quite full, and conse- 

upper Lever 




Fig. IGl. — A hydraulic boat-lift. 

quently ram a is unable to resist the pressure trans- 
mitted from ram b ; a rises and b sinks. Both tanks 
are provided with lifting gates at one end, with water- 
tight joints, and the sides of the canal reaches have 
similar doors. Provision is also made for sealing the 
joints between the tank and canal gates when a boat 
is about to enter or leave a tank. At Peterborough, 
in Canada, there is a lift of this kind for raising 400- 



314 CANALS AND IVATERWAYS. 

ton vessels 65 feet, in place of a flight of locks. Other 
examples are to be foimcl at Anderton, on the Trent 
and Mersey Canal, England; and at Fontinettes on 
the ^N^eufosse Canal, in France; and at La Lonviere 
in Belgium. 

Another kind of lift is nsed on the Ems-Dortmnnd 
Canal in Germany. In this case there is bnt one 
tank, for TOO-ton boats, mounted on the top of five 
enormous cylindrical floats, each 30 feet across and 
46% feet high. These floats move vertically about 
50 feet, in wells 138 feet, deep, surrounded by masonry 
walls a yard thick lined with iron, and have a com- 
bined buoyancy just sufiicient to lift tank, water, and 
boat (Fig. 162). 

The tank moves in vertical guides. It can be made 
to rise by partly emptying it, and to sink by filling it 
till it overcomes the buoyancy of the floats. But as 
this method would be attended by risks, the tank is 
further supported near the curves by four huge screws 
— spindles, 80 feet long and 11 inches in diameter, 
resting on solid towers of masonry. All four screws 
are geared together, and operated by a 150 horse-power 
electric motor, which is able to lift or lower the tank 
from one level to the other in about three minutes. 



CANALS. AND WATERWAYS. 



315 



IXCLIXES. 



Canal inclines resemble cable-operated railways in 
that both employ the principle of a descending load 




Fig. 162.— Principle of tlie boat-lift on the Ems-Dortmnnd Canal, Germany. 
F F are huge floats; s s are lifting screws, worked by p. 

hanling np an ascending load. The Foxton Incline, 
in Leicestershire, on the Grand Junction Canal, may 
be taken as typical of the barge-carrying railway. 
From the lower reach to the upper extends a slope 
100 yards long, on which are laid four rails for the 



3i6 CABALS AND WATERWAYS. 

^' up " and as many for the '' down " traffic. On each 
set of rails runs a large tank mounted on eight wheels. 
The two tanks are connected hy 7-inch wire ropes 
passing round drums in the engine-house at the top of 
the incline. At the foot of the slope, where the rails 
are submerged in the lower reach, the barge to be 
raised is floated into whichever tank is ready to 
receive it, and the end gate is closed. The engine 
is then started, and ten minutes later the tank attains 
the top of the incline, where its gates are brought into 
register with those of the upper reach, and the barge 
is floated out. This incline, designed by Messrs. G. 
and C. B. J. Thomas, replaces a flight of ten locks, 
and raises barges of TO tons through a height of 75 
feet. 

The most extensive installation of inclines belongs 
to the Morris Canal in the United States, wdiere there 
are twenty-three, w^ith an average lift of 58 feet. The 
largest is 1,100 feet long," and rises 100 feet. 

EXCAVATIXG OPEEATIOXS. 

Whether an existing water-course has to be canal- 
ized or an artificial waterway created, the operations 
necessary and the machinery used are in many 
respects the same. The engineer first goes over the 



I 



CANALS AND WATERWAYS. 



317 



ground very carefully with his level, determines the 
gradients, and decides the positions of the locks, lifts, 
or inclines, and what their height shall be. The fall 
of the ground requires deep excavating at the upper 
end of a reach, and embankments at the lower end. 
In Fig. 164 w^e observe the lowering of the original 
bed of the river just below the lock; in Fig. 163 the 







Fig. 1G3. — To illustrate the raising of a river's banks above a lock. 




Fig. 1G4. — The river bed deepened below a lock. 



raising of the banks above lock. When travelling on 
a canalized river, such as the Thames, you will 
notice that the banks rise so high above the w^ater 
at the upper end of a reach that a view of the 
surrounding country is precluded; wdiereas at the 
other end you may be actually above the adjacent 
water-meadows. 



CANALS AND WATERWAYS. 



319 



Both excavation and embankmg|k are done nowa- 
days by ingenious machines of great capacity. For 
the removal of dry earth, clay, rock, etc., from a new 
cut before water is admitted, a bucket dredge of the 
kind illustrated in Fig. 165 is widely used. Eails 
are laid beside the line of the cut for a travelling 
machine, which supports on one side a long arm 
round which travels an endless chain of buckets. 
These buckets dig out large chunks of material, con- 
vey them into the body of the machine, and either 
dump them into trucks for removal, or drop them 
on an endless belt running over a long arm on the 
side away from the excavation, which deposits them 
a considerable distance away from the machine to 
form a continuous dike flanking the canal. As the 
excavation proceeds, the bucket chain is gradually 
lowered until the full depth that the dredge com- 
mands is reached. Machines of this kind will remove 
100 cubic yards of soil in an hour, even when the 
surface is frozen hard. 

Another form of digger is the Clam-shell Grab 
(Fig. 166), with two semi-circular tooth-edged jaws 
which open during the descent, sink into the earth, 
and close together when lifted. On the ^ew Erie 
Canal works, near Eochesterj a huge grab of this 



320 



CANALS AND WATERWAYS. 



type, which gets a " bite " of 8 cubic yards every 
time, has been used with great effect. The grab is 

dropped from a structure 
that resembles a Goliath 
crane in that it straddles 
its workj and runs on two 
23arallel tracks laid on either 
side. The ends of the hori- 
zontal girder carried by the 
two towers project some dis- 
tance, so that the load may 
be dumped clear of the ex- 
cavation. The grab is most 
useful on long continuous 
stretches of similar work. 
A third class of machine is the Steam Shovel. By 
the courtesy of the Bucyrus Co. of South Milwaukee, 
I am enabled to give an excellent illustration (Fig. 
167) of one of their 9 5 -ton shovels at work in the 
Culebra cut on the Panama Canal route, loading rock 
into Avagons. The dipper has large teeth on its 
upjoer edge, and a flat bottom, and is mounted on 
the ends of a swinging armi Be it understood that, 
unlike the previously-mentioned machines, the steam 
shovel stands helow its work, and jnishes instead of 




Fig. IGG. — A grab for remov- 
ing earth from a cut. 



CA.VALS AXD WATERWAYS. 



321 



pulling upwards. The various motions performed by 
the machine are, to thrust the scoop against the bank, 
scrape it up the face, withdraw it, and open the 
bottom flap so that the contents may fall into the 
Avagon below. The largest scoops hold five cubic yards, 




Fig. 167. — A steam-shovel at work on the Panama Canal. 
(.Photo, The Biicijrus Co.) 

and make four strokes a minute. A single shovel 
can dig and load material at the rate of 6,000 yards 
per day of ten hours, provided that the " dirt " car 
trains are organized so as to keep it steadily employed. 
Seventy-seven Bucyrus shovels are busy on the Panama 
Canal, and without them it would be impossible to 



322 



CANALS AND WATERWAYS. 



do the work in a reasonable time, if at all. It has 
been calculated that one machine, operated by three 
men, can shift as much dirt in a day as 2,400 men 
using picks and shovels. 

When the cut has been well started it is, under 
some conditions, filled with water to take floating 
excavators, which also we will review briefly. The 




Fig. 168. — A barge dredger, showing chain of buckets, Avorking round a mov- 
able ladder, projecting through the bottom. 

hucJvet dredge (Fig. 168) consists of a continuous 
chain of buckets working round a beam which projects 
through the bottom or from the side of a barge, and 
is raised or lowered by a tackle. 

Passing over the dipper-, and grab, respectively 
resembling the steam shovel and grab for dry material, 
we come to the suction dredge, which is peculiarly 



I 



CANALS AND WATERWAYS. 



323 



adapted for working in sand and silt and gravel. 
The material is sucked up hj a centrifugal pump 
through a large pipe suspended from a beam project- 
ing from a vessel, which maintains it three or four 
feet above the surface of the bottom. A gigantic 




Fig. 1G9. — The revolving knives on the nozzle ol a :>ucLi<ju dredge. 
(From a photograph in "'Cassier's Magazine.") 



sand-pump dredge has been constructed lately for the 
Mersey Docks and Harbor Board by Messrs. Cam- 
mell Lairds. It lifts 10,000 tons of sand in fifty 
minutes from a depth of 70 feet, and does yeoman 
service in keeping the Mersey channels free for the 
passage of the leviathans that use the Liverpool 



324 CANALS AND WATERWAYS. 

docks. On the Erie Canal, where it traverses Oneida 
Lake, the dredges employed have suction pipes ter- 
minating in a series of long, flat knives, arranged in 
a drum (see Fig. 169) like the vanes of a revolving 
^vind-cowl for a chimney-top. The knives are rotated 
sliarply by shafts and bevel gearing, and bite into 




Fig. 170. — A dredge depositing " spoil " ou tlie bauks of a canal by long 
travelling belts. 

the sand or clay and mix it with water for the pipes 
to carry away. 

Dredges of the ^^ hopper " variety fill themselves 
up with spoil, and transport it oat to sea to be dumped. 
Where there is no sea exit, the stuff is transferred to 
the bank by endless belts working over long horizontal 
arms (Fig. 170), or through pipes, either suspended 



CANALS AND WATERWAYS. 



325 



from a mast 011 the dredge, or supj)orted on floating 
pontoons. The " long shoot " type, illustrated by Fig. 
171, was used for most of the work done in the Suez 
Canal, the shoots being as much as 230 feet in length. 
Pontoon-supported pipes have flexible joints to allow 
of motion in the pontoons. The water with which the 
sand, mud, etc., is mixed, drains from the bank back 
into the canal. 

When rock has to be treated by floating dredges, 
the bottom is first shattered either by blasting charges, 
or by heavy steel-shod breakers dropped from the 
dredge. 

All the machines which we have noticed are mar- 
velously powerful and effective, and lighten the work 
of construction to an extent which early canal-builders, 
whose apparatus was the wheelbarrow and shovel, 
could hardly have dreamed of. 

PEOTECTIXG BAXKS. 

The passage of a boat or ship causes a ^^ wash " 
which would speedily damage a canal's banks were 
they not protected by stonework, concrete, fascines, 
or some other kind of durable surface. In Holland, 
where stone and timber are scarce, the wickerwork 
fascine is largely employed, not merely for the pro- 



L 




CANALS AND WATERWAYS. 



327 



tection of embankments, but in tlieir construction. 
Extraordinary fascine operations, which we may 
notice in passing as of peculiar interest, are carried 
out from time to time at the mouths of the Mississippi 
River, where the discharge of water is enormous, 
especially at the flood season, and incessantly erodes 
the banks. The government engineers prepare huge 
floating mattresses of willow poles and steel cables, 
load them carefully with rock, and sink them on to 
the river bed at points where the bank is being eaten 
away by the current. One of these mattresses, made 
to protect the banks at Memphis, measured 775 feet 
in length and 254 feet in width, and had an area 
of 4% acres. The sinking of this vast structure was 
a very delicate operation, as the ballast had to be 
distributed all over it quickly, so that it should settle 
evenly. 

SHIP CANALS. 

The first great ship canal opened was the Suez, 
begun in 1859 and completed in 1869. The canal 
is notable as being the longest in existence (90 miles) 
and, except for the Corinth Canal, the only example 
of an artificial ship waterway lockless throughout its 
entire length. Two-thirds of its course lies through 
shallow lakes. The material excavated was sand. 



328 CANALS AND WATERWAYS. 

occasionally varied by hard rock. Over 100,000,000 
cubic yards of spoil was transferred by dredges from 
the channel to the banks. It has a surface width of 
108 feet, and is 31 feet deep, and is able to pass the 
largest vessels in about 18 hours. Built under the 
management of the famous but ill-fated M. Ferdinand 
de Lesseps, it has entirely revolutionized sea communi- 
cation between Europe and India and the east of Asia. 

The Manchester Ship Canal, completed in 1894, 
Avas a vastly more difficult undertaking. It connects 
Manchester with the Mersey near Liverpool, 35^ 
miles away. For 13 miles from the sea entrance it 
follows the left bank of the Mersey, from which it is 
separated by earth embankments, rubble mounds, and 
concrete walls. One of the mounds, 1^ miles long, 
rests on tAvo continuous parallel roAvs, 78 feet apart, 
of piles driA^en doAA^n into the sand Avith the help of 
a Avater-jet. One hundred miles of timber, 12 inches 
square, AA^ere used in this AA^ork. A total rise of 60 
feet is effected by four locks, distributed OA^er the 
last 15 miles, from Eastham, Avhere the tidal portion 
ends, to JManchester. 

The channel is entirely artificial, but it has been 
made capacious enough for 9,000-ton A^essels. Over 
10,000,000 tons of sandstone rock had to be remoA^cd, 



CANALS AND WATERWAYS. 



329 



and three times as niiicli sand, claj, and sliale. At 
Barton, where the Bridgewater Canal crosses the line, 
there is a very interesting swinging aqueduct, which 
revolves a 234-foot length of the minor canal on a 
central pivot to permit the passage of ships (Fig. 




Fig. 172. — Swing aqueduct on the Bridjewater Canal, where it crosses the 
Manchester Ship Canal at Barton. 

172). The Manchester Ship Canal is one of the 
greatest triumphs of canal engineering. 

Xext on the list comes the Kaiser WWielm Canal, 
opened in 1895, to link up the Baltic and Xorth Seas. 
Its original purpose was strategic, to enable the 



330 CANALS AXD WATERWAYS. 

German fleet to pass into and out of the Baltic 
throngh German territorv, but it has also proved very 
valuable commerciallv. It has a length of 61 miles 
and a depth of 291^ feet. The total excavation was 
100,000,000 cubic yards. Where the canal traverses 
the peaty bed of the Kuden Lake it was necessary 
to form sand embankments on each side of the peat, 
and, when they had sunk through the peat, to dredge 
a waterway between them. 

Among fresh-water canals those which connect the 
great lakes of Xorth America with one another and 
the St. Lawrence, Hudson, and Mississippi rivers are 
the most important. A sketch map (Fig. 173) is 
appended to show the positions of the most notable 
canals existing and projected. The latter are indi- 
cated by dotted lines. 

One of the shortest of canals, being but little more 
than a mile in length, the " Soo," is also one of the 
most valuable. It passes some 20,000 ve-ssels a year, 
with a tonnage of 36,000,000 tons, round the Sault 
Sainte Marie Falls, and so gives an outlet to the trade 
of the country round Lake Superior, including the 
vast quantities of iron ore shipped from the Mesabi 
region. The Detroit River connects Lakes Erie and 
Huron, and the Wolland Canal lowers vessels from 



CANALS AND WATERWAYS. 



331 



Lake Erie to Lake Ontario. Tlie Erie Canal, 350 
miles long, allows barges to travel from Buffalo on 
Lake Erie to Albany on the Hudson Kiver, and so to 
tide water. This canal lias developed enormously the 

6" 




Fig. 173. — Map showing some of the chief existing and projected canals in 
North America. 

industries of ^N'ew York, and made that State the 
richest in the Union. 

On the Canadian side of the boundary there is a 
scheme for spending £20,000,000 on a 430-mile 
waterway, which will ultimately transport vessels of 
large size from Lake Huron to the St. Lawrence. 
Starting from Georgian Bay in the lake, steamers of 



332 CANALS AND IVATERVVAYS. 

8,000 tons burden will ascend the French Kiver to 
Lake E^ipissing, rising 56 feet through locks. From 
l^ipissing to the chain of lakes which are the head- 
waters of the Mattawa, a tributary of the Ottawa 
River, they w^ill pass through an artificial canal, and 
then drop 620 feet to tide-water in the St. Lawrence 
down natural channels which are to be canalized with 
twenty-three locks. 

This canal will put the world's ports in easy com- 
munication with the Great Lakes, and shorten the dis- 
tance from Chicago to Liverpool by 700 miles, or 414 
days' sailing, as compared with the Erie Canal route ; 
and by 3% days as compared with the Lake Huron 
and Welland Canal route. It has been remarked that 
Avhat the Canadian Pacific Railway was to an earlier 
generation, the construction of the Georgian Bay- 
Ottawa Canal is to the men of to-day. Both commer- 
cially and strategically the value of the new passage 
will be incalculable, as it will cater for the traffic of a 
region almost as large as Europe, while in the unfor- 
tunate event of war it would enable warships to ascend 
to the great Lakes. Little wonder, therefore, that the 
Canadians are prepared to sink a huge sum of money 
in the completion of a splendid waterway which 
iN'ature left not quite finished. 



Chapter XVII. 

THE PANAMA CANAL; IRRIGATION CANALS; 
A TUBE CANAL. 

An intolerable obstacle to shipping — M. Ferdinand de Lesseps forms 
a company to pierce the Isthmus of Panama — Difficulties en- 
countered — The French cede their rights to the United States — 
The present scheme — The Gatun Dam — ^Work in the Culebra 
cut — The Panama Canal the greatest of all engineering feats — 
Irrigation canals — A steel-lined canal at Kom Ombo — The Un- 
compahgre Valley project, Colorado — A long tunnel required — 
A projected tube canal over the Alps. 

THE cutting of a canal through the Isthmus of 
Panama is a task that had sooner or later to 
be faced by civilized nations. The labor and cost 
of taking ships round the Horn to get from east to 
vest of the American continent by sea could not be 
endured indefinitely. In 1879^ M. Ferdinand de 
Lesseps, who by his Suez Canal had already made the 
rounding of the Cape of Good Hope unnecessary for 
eastward-bound European ships, persuaded the French 
to invest a huge sum in a scheme for piercing the 
isthmus with a sea-level canal. We need not repeat 



334 



THE PANAMA CANAL. 



the sad story of corruption, mismanagement, and mis- 
calculation which, in combination with terrible phys- 
ical obstacles, brought disaster to the thousands of 
peoj^le who had trusted the words of the aged engineer. 
Work on the canal w^as not stopped completely, but 
in 1905 the French company was glad to retire in 
favor of the United States Government, which bought 
it out for a sum of $10,000,000, and also purchased 
from Colombia for $10,000,000 a strip of territory 
extending five miles on each side of the route of the 
canal from ocean to ocean. 

The main physical difficulties with which the French 
had contended unsuccessfully were — (1) the unheal th- 
iness of the country; (2) the great Culebra Hill; and 
(3) the Chagres River, crossing the line of the canal, 
a stream frequently swollen by tropical rains. 

The first killed workmen by the thousand; the 
second required a vast amount of excavation; and the 
third frustrated all attempts made to confine its 
waters. To the credit of the French be it said that 
before they abandoned the scheme they had excavated 
at all points a total of about 85,000,000 cubic yards 
of material. 

When the Americans took the business over, tlic 
matter of deciding whether the canal should be a sea- 



THE PANAMA CANAL. 



335 



N\/300 OUIOVd 




level or a locked high- 
level 



long debated. 



waterway was 
In 

1906 the second al- 
ternative was adopted 
by Congress. The 
final plan, in accord- 
ance with which tlie 
engineers are now 
working, is shown in 
Fig. 174. 

The canal will be 
51 miles long, extend- 
ing from a point op- 
posite Colon on the 
Atlantic coast to a 
point 3 miles or so 
from land in Panama 
Bay in the Pacific. 
For almost 30 miles its 
surface level will be 
87 feet above the sea. 
At Gatun a double 
flight of three locks 
will raise vessels to a 



NV330 ViN\m\f 




Fig. 175. — At work in the Culebra cut, Panama Canal, 
dredges to a depth of 152 feet. 
(Photo, John Geo. Leigh, Esq.) 



Ground removed by 




Fig. 17G. — A cableway in the Empcrador cut. 
(Photo, John Geo. Leigh, Esq.) 



THE PANAMA CANAL. 



337 



large artificial lake created by impounding the waters 
of the Chagres River by a dam which will be the 
largest of its kind in the world — Y,900 feet long at 
the crest, 3,100 feet thick at the base, and 370 feet 
wide at the top, and containing 30,000,000 tons of 
earth. In the face of such figures even the Ashokan 
Dam seems a small aif air ! Sluice gates in the dam 
will regulate the height of the water in the great in- 
land lake and control the floods of the Chagres River. 
Across the lake a channel will be dredged to Bas 
Obispo at the southern end, where begins the cut 
that attains its greatest depth in the Culebra Hill. 
The Culebra is the biggest problem of all. From the 
top of the saddle to the bottom of the canal is a per- 
pendicular distance of about 280 feet, and the maxi- 
mum width of the cut is calculated at about 600 feet. 
The French removed many millions of tons of stuff 
at this point, but the Americans must remove twice 
as many again. On this cut thirty of the steam 
shovels described on a previous page are at work 
eating out terraces in the sides, which are of hard 
basaltic rock. At Pedro Miguel the canal steps down 
31 feet, and farther on, at Miraflores, there are two 
locks, each having a 31-foot lift, to lower or raise 
vessels from sea-level. All locks are duplicated. 

22 



THE PANAMA CANAL. 2>?>9 

From the Atlantic terminal to the Gatnn Dam 
the channel is to be 500 feet wide and 41 feet deep 
at mean tide. From Gatnn to Culebra cntting, a dis- 
tance of 25 miles, the width will nowhere be less than 
300 feet, and in the cnt itself, though the top width 
will decrease to 200 feet, the sides are to be almost 
vertical, to allow two of the largest vessels to pass 
one another easily. From the Miraflores lock to the 
Pacific terminal the second sea-level stretch will have 
a width of 500 feet. 

By March 1, 1908, the Americans had excavated 
28,411,879 cnbic yards, more than half of this 
quantity being taken from the Culebra section. On 
that date there remained 100,000,000 cubic yards 
to be shifted. During October of 1907 nearly two 
million cubic yards were excavated from the canal 
prism, thanks to the energy of the directing engineers 
and the great capacity of the machinery employed. 
With so many labor-saving devices the force of work- 
men is kept much smaller than was originally ex- 
pected; yet there are some 27,000 employes on the 
pay-rolls. 

It is expected that the canal will be finished in 
1912, at a total cost of about $275,000,000. The 
effects of the opening of the canal on commerce 



340 IRRIGATION CANALS. 

and strategy cannot be calculated, but some results 
seem to be assured — that a huge amount of traffic 
"will be diverted from the Suez route; that the trans- 
continental railways will be affected; that the United 
States, as controllers of the canal, and possessing a 
means of throwing their fleet from one ocean to the 
other in a fraction of the time now required for the 
doubling of the Horn, will greatly strengthen their 
position as a naval Power. Panama will be the great 
gateway between east and west, and will play an 
important part in shaping the future history of 
nations. Considering the issues involved, the magni- 
tude of operations, and their enormous cost, the mak- 
ing of the Panama Canal may be written down as the 
greatest engineering feat yet undertaken by man. 

IRKIGATION CANALS. 

I^ot less important than boat and ship canals are 
those which distribute water in arid and semi-arid 
countries to make agriculture possible and profitable. 
In India some 45,000,000 acres have been won from 
the desert by irrigation canals; in the United States 
10,000,000 acres; in Egypt 6,000,000 acres; and in 
other parts of the world probably as great an area 
as in these three countries combined. We have noticed 



IRRIGATION CANALS. 341 



earlier in the book some of the huge dams built to 
impound water for irrigation purposes, and we may 
well spare a page or two for some of the most inter- 
esting canal enterprises designed to utilize water stored 
in this manner. 

Irrigation canals differ from navigation canals in 
that they have no locks, being merely water channels, 
but resemble them as regards their construction, 
though in some cases they have special features. For 
instance, at Kom Ombo, 40 miles north of the Aswan 
Dam, a district is being reclaimed which lies 75 feet 
above the level of the Nile, and could not be irrigated 
in the ordinary manner by gravitation. The w^ater is 
therefore raised by pumps into a reservoir, whence 
it flows through a huge semi-circular steel trough, 
a mile long and 15i/> feet in diameter, to the plain, 
to be distributed by secondary canals and ditches. 

The trough is built up of steel plates % i^ich thick 
in seventeen 300-foot lengths. Every thirty inches 
the plates are stiffened by angle bars on the outside, 
and braced together at the top by crossbars. (See 
Fig. 178.) As a continuous trough would be much 
distorted by contraction and expansion under a trop- 
ical sun, each section rests at the ends on masonry 
supports shaped to fit it exactly, and containing 



iliilliiU;, 




IRRIGATION CANALS. 



343 



grooves filled with tarred and tallowed rope, to make 
a watertight packing over which the section may slide 
a little. The ends of two sections are 6I/2 feet apart. 
In the foreground of Fig. 179 we see a masonry sup- 
port partly built and one of the overhead gantries, 
used for handling the plates. 




Fig. 179. — Kom Ombo Canal. Riveting the plates. The sides have not yet 
been bankeil up with sand. In the foreground is one of the masonry sup- 
ports on which the sections rest. 

{Photo, ''The Scientific Amei'ican.^') 

During the riveting of the plates each section was 
supported by timber cradles set 30 feet apart. When 
completed, its level was carefully adjusted with screw- 
jacks and sand, tightly rammed, was banked up on 
either side to takelits weight and protect it externally ; 
then the jacks were withdrawn. The inside received 



IRRIGATION CANALS. 345 

p. coat of bituminous paint, applied by night. The 
main difficulties encountered by the engineers were 
the strong desert winds, which scoured the sand from 
under the trough, and the quarrelsomeness of the 
native workmen, some 7,000 in number, who were 
apparently more handy with their knives than with 
the pneumatic riveting machines, and averse to night 
Avork. 

The canal passes twelve cubic metres of water a 
second, and already has been instrumental in con- 
verting 12,000 acres of arid waste into thriving cotton 
aaid sugar plantations, interspersed by prosperous 
villages. 

THE UXCOMPAHGEE VALLEY PROJECT^ COLORADO. 

The Gunnison River, a tributary of the Colorado, 
flows at the bottom of a caiion nearly 2,000 feet deep, 
with almost yertical sides. Some miles away, and 
at a much lower level, lies the yalley of the Uncom- 
pahgre, a sage-brush desert (Fig. 180). Between the 
two rises a mountain range. In order to carry the 
Gunnison's water to the desert, a tunnel 5^/2 miles 
long has been driven through the solid rock, sand- 
stone, shale, and lime in the face of great difficulties. 
From the south portal runs a canal 12 miles in length. 



343 A TUBE CANAL. 

wliicli carries 1,300 feet of water per second to the 
point of distribution. Owing to the nature of the 
soil the sides of the canal are concreted throughout 
(Fig. 181). This canal will bring 200 square miles 
of desert under cultivation. 

In Idaho, California, Arizona, l^evada, Wyoming, 
Montana, and N^ew Mexico schemes of equal impor- 
tance to the Uncompahgre are in operation; but they 
are all surpassed by the diversion of the Bow River, 
in Alberta, Canada, into a canal 120 feet wide at the 
waterline, 60 feet wide at the bottom, and 10 feet 
deep, which will irrigate an area of about 4,500 
square miles. 

A TUBE CANAL. 

A well-known Italian engineer, Pietro Caminada, 
has brought forward a project for a canal to join 
Genoa in the Mediterranean with the ^NTorth Sea, 
across the Apennines and Alps. For a large portion 
of its length the 6anal will consist of waterways 
already open, but in the mountainous regions, where 
the rise and fall of the course is sudden, he proposes 
to make use of gigantic slanting tubes in place of the 
ordinary open channels. 



^''^ 




Fig. ISl. — Comenting the sides of the Uucompahgre Canal. 




^^^^H 






Fig. iS^ 



■iiie Cedar Creek Poital cut of the Gunnison Tunnel, Uucompahgre 
Valley project. 
{Photos, "The World's Work.''') 



348 



A TUBE CANAL. 



If joii put a cork in the bottom of a tube, and 
stand the tube upright and fill it with water, you 
illustrate the principle of the canal lock which has 
been described on a previous page. The corh is lifted 
but not advanced. 

¥ow empty the tube, slant it, and fill it again. 
]^ot so much water is required this time to bring 
the cork to the upper end. The cork has not, indeed, 




Fig. 183. — Diagram to show principle of Caminada's proposed Tube Canal 
across the Alps from Germany to Italy. 

risen vertically as far as in the first case, but it has 
been -moved forward a considerable distance. 

Imagine, now, in place of the cork, barges of 600 
tons burden, and the tube to be expanded to a diam- 
eter of about 50 feet, and you have a fair idea of 
Caminada's system. The tubes will not be continuous, 
but interrupted at certain intervals by chambers 
closed at each end by doors. This will make it pos- 
sible to raise or lower a number of barges simulta- 
neously in different sections of the line. To promote 



A TUBE CANAL. 349 

speed the line will be doubled/ one " track '' for 
ascending and tbe other for descending. 

Fig. 183 is a sketch to show how the system 
works. In the lowest section a barge has risen to 
the chamber at the top, which it is entering through 
the opened gate. In the middle section another barge 
is rising, and the uppermost section is being emptied 
to receive it. The water let out from one line of 
tubes serves to fill the sections in the other line. 

Guides projecting upwards from the barges to 
engage with bars on the roof of the tubes will help 
to direct the craft. A model of the system on a scale 
of one-tenth has been constructed, and found to work 
so perfectly that much attention has been dra^vn to 
the project, which is calculated to transport fifteen 
million tons from the Mediterranean to the ^orth 
Sea in a single year, at a speed which would compare 
favorably with that of the freight trains that are 
the carriers at present. 



Chapter XVIII. 
HARBOR WORKS. 

Artificial harbors — Force of waves — T^^i^es of breakwaters — Methods 
of construction — Building-out — Titan cranes — Gantry method — 
The Dover harbor works — How the work was done — Block- 
making — Building the gantries — Preparing the ground — Di\'ing 
bells — The island breakwater — ^The Admiralty Pier extension — 
Aprons — Prince of Wales Pier. 

PEACTICALLY every coimtrv tliat lias a sea- 
board has been provided by nature with one 
or more harbors in ^vhich a fleet may ride safely, 
unvexed by storms that rage outside. Political 
reasons, on the other hand, have compelled maritime 
powers to supplement the natural protection of their 
harbors with artificial works designed to prevent the 
entrance of hostile ships should war arise, and also 
to create entirely artificial roadsteads at points on 
the coast where the waves have had free play. 

The force of a big ocean roller is enormous. 
Experiments made on the coast of Dunbar, Scotland, 
have recorded a maximum blow due to the water equal 



HARBOR WORKS. 351 

to 3% tons to the square foot, 31% tons to the square 
yard. The design of a mole or breakwater differs 
widely from that of a dam, subjected to a steady cal- 
culable pressure. The roughest buffets fall upon 
that part of the mole immediately above and below 
the normal water line, so that the masonry must be 
solid and thick to the top, and able by its very weight 
to withstand the utmost force of the waves. 

Difficult indeed is the task of the engineer who has 
to raise great stone piles in despite of the elements, 
and vast are the quantities of material needed for 
his work. It is not exceeding the truth to say that 
in its struggles with the sea modern engineering is 
seen at its best. 

TYPES OF BREAKWATERS. 

The form that a breakwater takes depends largely 
on local conditions and facilities. Sometimes it is 
merely a long, wide pile of stones or concrete blocks 
tipped at random from barges until they rise above 
high-water level; or again it may be a stone pile 
capped with solid blocks laid in order ; or a wall built 
of blocks from the sea bottom. 

Algiers breakwater illustrates the first type. For 
good examples of the second we turn to Portland 



35 



HARBOR WORKS. 



Plarbor, where nearly 4 square miles of sea are all 
but encompassed by the shore and 3^/4 miles of mole. 
(A section of the work is given in Fig. 184.) At 
Gibraltar 410 acres are sheltered by blocks laid on 




. Z86V/- ^ 

Fig. 184. — Section of Portland Breakwater. 

rubble mounds. An excellent illustration of the wall 
type is found in the new Admiralty Harbor extension 
works at Dover, on which we shall concentrate our 
attention in the present chapter. 

— -45^ 




Fig. 185. — Section of Plymouth Breakwater. 



METHODS OF CONSTRUCTION. 

A simple rubble mound is formed by dropping 
the materials from hopper barges on to the desired 
spot. For block walls two methods are employed, 
the services of giant cranes being required for both. 

The " building out " method. To illustrate this 
we may turn back for a moment to the new harbor 



HARBOR WORKS. 353 

at Gibraltar. One of the moles is detached, or 
unconnected with the shore. A huge steel caisson, 
33 feet wide, 101 feet long at the bottom (tapering 
to 76 feet at the top), and 48% feet high, was con- 
structed in England, towed to Gibraltar, and sunk in 
position on the top of a rubble mound. Thousands of 
tons of concrete were poured into this mould, till 
a single solid mass was formed, and on this the engi- 
neers raised a " Titan '' crane, which may be briefly 
described as a large girder pivoted on a revolving turn- 
table supported by a lofty bridge-shaped truck. Fig. 
186 illustrates a crane of this kind. The longer arm, 
having an ^' overhang '' from the centre of the turn- 
table of anything up to 100 feet, does the lifting; the 
shorter arm carries the engine and gear for hoisting 
and moving the crane on its rails, and a counterweight 
which is shifted to balance the load. After the 
Gibraltar Titan had been erected, it proceeded to lay 
blocks in steps against one end of the caisson until 
it had made a fresh footing for itself, and then moved 
on to the new work to afford room for a second Titan. 
The two travelled away from each other until the 
mole was completed. 

Under certain conditions this method is very 
advantageous, as the mole automatically advances 

23 



•354 



HARBOR WORKS. 



itself, and the cranes run on a solid foundation, 
along which thej can be withdrawn in stormy 
weather. It has one disadvantage, however — that 
where the foundations for the blocks must be exca- 
vated and levelled, construction is delayed, as the 
cranes can do but one thing at a time. Consequently 




Fig. 18G.- — A Titan cruue iayiiig au Apron Bioek. 

where circumstances prove favorable recourse is had 
to the second, or 

Gantry method. Rows of piles are driven on 
either side of the line to be occupied by the blocks, 
to support platforms or gantries for " Goliath " 
cranes — movable bridges fitted with winding and 



HARBOR WORKS. 



355 



propelling meclianism, situated directly over their 
work. The construction of the gantries is very 
expensive, but its cost is often more than saved by 
the ease afforded of distributing the necessary oper- 
ations among a number of Goliaths, all employed at 
one and the same time. 



THE DOVER HARBOR WORKS. 

In 1895 Dover, the English port of the chief 
cross-Channel route, boasted only a single pier, 
built for the Admiralty in the years 1863-71. 




4200' 
5oorh,or Wand Breakwater 



Fig. 187. — Plan of the New Admiralty Harbor, Dover. The works marked in 
solid black have been carried out by Messrs. S. Pearson and Son. 

It is 2,100 feet long. In that year it was decided 
to create a ^N'ational Harbor by extending the 
pier 2,000 feet, building an island breakwater 
east and west 4,200 feet long, and protecting the 



356 



HARBOR WORKS. 



eastern side with a shore arm of 
adjunct to the sea works an area of 22 acres of shore 
was reclaimed under the cliffs adjacent to the east 
arm. The works then proposed, and since carried out 
by Messrs. S. Pearson and Sons of Westminster, are 
shown solid black in the plan, Fig. 187. 

A section of one of the three breakwaters is given 
in Figo 188. The depth of the water at Dover varies 
from 61 feet to 42 feet, according to the state of 
the tide. The breakwaters taper slightly towards the 
top, which in the case of the Admiralty Pier extension 

and east arm is 
crowned on the seaward 
side by high parapets 
to protect passengers. 
On a level with the 
bottom of the parapet 



4iM_. 




IS a 



'' bull- 



nose, 



or 



Fig. 188. 



-Section of breakwater, Dover 
Harbor. 



large blunt lip, bend- 
ing out towards the 
sea, so as to deflect the 
water and hinder it from washing over. The greatest 
width of breakwater at the foundations is about 
57 feet, the greatest height 90 feet. As one walks 
on the breakwaters it is hard to realize that the wide 



HARBOR WORKS. 



357 



platform is merely the top of a wall, and that the 
wall itself is as high as a five-storied house. Their 
great length makes the structures, or rather that part 
of them which rises above water, seem almost insig- 
nificant in the distance. It is only when you come 
to close quarters with the moles, and see what they 
are built of, and how they are built, that you under- 
stand j)roperly the titanic nature of the undertaking. 

HOW THE WOEK WAS DONE. 

The contractors began operations on the Admiralty 
Pier extension, and on cutting back into the chalk 
cliffs along the easterly half of the strip of shore 
included in the harbor. Hundreds of men, roped 
together, attacked the cliff face, drilling holes and 
blasting do^vn great masses of the dazzlingiy white 
substance to form a solid platform well above the 
sea. .As the shore was at this time exposed to the 
full violence of the waves, great quantities of the 
chalk were carried away until a retaining wall of 3-ton 
concrete blocks had been erected on the sea edge of 
the reclamations by cranes running along platforms 
on piles driven on the cliff side of the wall. As the 
wall progressed the space behind it was filled in, and 
eventually the contractors secured an area 3,850 




I 



HARBOR WORKS. 



359 



feet long and 250 feet wide as a site for blockmaking 
yards, work shops, repair shops, foundries, and stores 
of all kinds. A strong wooden barricade, 8 or 9 feet 
high, was raised to protect the yards from the surf 
of the waves driven in bv south-westerly gales. 

BLOCKMAKIXG. 

As the breakwaters are almost entirely constructed 
of blocks, we will glance at the process of manufac- 
turing these gTeat rectangular masses of concrete. 
There were two main block yards, one at the west 
end of the harbor for the Admiralty Pier extension, 
the other on the reclaimed ground for the East and 
Island breakwaters. 

A picture of a yard in operation is given in Fig. 
189. The blocks vary in weight from 3 to 42% tons, 
the largest measuring 14 by 7% by 6 feet. Gravel, 
sand, and cement, mixed in certain proportions, form 
the concrete from which they are shaped in wooden 
moulds, open at the top and having two sides remov- 
able so that the block may be extracted easily. 

The sand and gravel was fetched from points on 
the Kentish coast by rail to the top of the cliff, shot 
into great hoppers, and conveyed down the face on a 
cable-operated inclined plane, with four tracks, the 



360 HARBOR WORKS. 

descending laden cars hauling np empty cars. From 
the plane the cars pass on to a charging platform, 
where they are tipped into other hoppers, which auto- 
matically deliver the materials into big mixers run- 
ning underneath on six sets of rails commanding an 
equal number of rows of block-moulds. Immediately 
after receiving its charge of six parts of gravel and 
sand to one of cement, and a due amount of water, 
the mixer begins to travel towards its mould, churn- 
ing up the contents as it moves along the rails, so that 
no time shall be lost. Arriving at the mould — which 
has been previously well greased, for the same reason 
that a cook greases her cake tins — the mixer empties 
its load, and then returns to the charging platform. 
As every charge is tipped, the concrete is well rammed 
into the mould, and when the mould is full the sur- 
face is struck off with a straight-edge. A week is 
allowed for the material to set. Then along comes the 
Goliath crane spanning the moulds, lifts the block 
out of its mould, which has been loosened for the 
purpose, and stacks it at one end of the yard. You 
will see a pile of stacked blocks in Fig. 189. 

After another month or so it has hardened suf- 
ficiently to be fit for use. 

For the ea?7 handling of the blocks, two oblong 



HARBOR WORKS. 361 

holes, inclined towards one another, are laionlded in 
the concrete by inserting wooden bolt-cores, removed 
when the concrete has set. Into each hole is inserted 
a bar called a lewis-bolt, furnished with a T-head 
at the lower end, which is given a qnarter-turn to 
grip the block underneath, where there is a recess 
somewhat deeper than the head. The shackles on the 
upper ends of the bolts are then passed over the double 
crane hook of the Goliath. 

Fig. 190 shows a block suspended by its bolts. 

About 64,000 blocks, averaging 30 tons in weight, 
were used in the breakwaters — 1,920,000 tons in all. 
Add the blocks for the retaining wall of the reclama- 
tion, and the apron blocks laid on the seaward side 
of the breakwaters, and we get a grand total of about 
3,000,000 tons of masonry. 

Before closing this section I should mention that 
all outside blocks have their sea-face covered by 
granite ashlar work, built up inside the moulds before 
introducing the concrete. A glance at ~Fig. 192 gives 
us a good idea of the facing and the method by which 
it is bonded v\uth the concrete, " stringers," or longi- 
tudinal blocks of granite, alternating Vv'ith " headers," 
Avhich show their ends and project back into the body 
of the block. 



-rw 


^'m 




1 




1 


[ 


rlQ 




fU 




^11 




ill 




ll 


j 

f 

^ 1 


J 


1 


^"^48 








5' 






1 < 


l^^^^i 




^A 




/ ^ 




f ^ , ^JbI 






f 






^ ^^^Hg 


? 




1^ 






HARBOR WORKS. 363 



BUILDIXG THE GATs^TEIES. 

Before any work could be done on the break- 
waters, the contractors had to erect the shore end of 
the gantries, to accommodate the Goliath cranes. As 
the latter weigh 100 tons each, without load, which 
may add another 50 tons, these platforms required 
very substantial support. 

First were driven in with a 2-ton ^' monkey '^ 
great iron-shod wooden piles, 100 feet long and 
from 18 to 20 inches square, in groups of six, three 
on each side of the line of the future block-work. 
Fifty feet separated each group from that next ahead, 
and there was a clear 70 feet laterally between the 
two sub-groups. Oregon pine piles were used, until, 
on account of the damage done to them by sea-worms, 
and of their lightness — which made them float when 
detached, to the danger of shipping — it was decided 
to replace them with sticks of Tasmanian blue gum, 
which is immune from the sea- worm, and naturally 
sinks. Half a million cubic feet of this wood were 
selected and ordered by the contractors' expert, who 
made a special journey to Tasmania for the purpose. 
We may mention in passing that the harbor works 



HARBOR WORKS. 365 

consumed one and a half million cubic feet of timber 
in all. 

On the top of the piles were placed short cross 
girders, to carry the three main longitudinal lattice- 
work girders connecting the groups in each gantry. 
The gantries were braced diagonally by strong ties, 
and laterally by lattice girders — the men are seen 
standing on them in Fig. 191 — and covered with a 
heavy timber flooring to form a base for the two 
Goliath tracks, 100 feet apart, and for the railroad 
tracks over which the blocks were brought from the 
yards on the frames of discarded six-wheeled engine 
tenders. Ordinary four-wheeled trucks were too light 
for the work. 

PREPARING THE GROUND. 

As soon as a considerable length of staging had 
been erected by the pile-drivers working on the 
outward end, a Goliath was established to operate the 
great clam-shell grab (see Fig. 191, on left), which, 
if it got a good bite, would bring up 5 tons of stuff. 
When the ground proved too hard for it, a ^' breaker '' 
— a solid block of iron Avith three projecting teeth — 
was used to pound the sea-bed into pieces which the 
grab could gather. 




Fig. 192. — The west end of the Island Breakwater, Dover Harbor Works, 
showing granite masonry facing of blocks. 




Fig. 193. — Inside a diving-bell. 



HARBOR WORKS. 367 

Behind Goliath ISTo. 1 came that for working the 
diving bells — steel boxes 17 feet long, 11% ^eet wide, 
and 6% feet high (the largest), provided with seats 
and a wide tray to contain the material excavated. 
Four men could work comfortably inside the largest 
40-ton bells. 

The bell moved in stages from side to side across 
the end of the wall, against which one side rested 
to keep it in the true line. The bells were lighted 
electrically, and furnished with telephones connecting 
with the crane platform. When a full breadth had 
been excavated and levelled, the Goliath moved on 
and made way for a third and fourth engaged on 
laying the blocks, the under-water courses of which 
required the services of divers. In Fig. 196 we see 
the boats attending two groups of clivers, and, looking 
more closely, the crane ropes suspending a submerged 
block. Each diver informed the craneman above by 
signals when the block was in its exact position, and 
when to lower it on to its bed. He then gave the 
lewis bolts the necessary twist to disengage them, and 
they were hauled up. 

The blocks are " keyed " together by bags of 
cement lowered into semicircular grooves moulded in 
the faces so as to come opposite one another in pairs 



368 



HARBOR WORKS. 



(Fig. 195), and further secured by iron bars where 
they form the ends of the breakwaters. 

Eapidity of work was necessarily dependent on the 
weather. In rough seas nothing could be done ; when 
the water was calm, operations continued night and 
day. The proper balancing of the different stages of 




1 I r 

Fig. 194. — Diagram showing piles supporting platform for block-laying 
Goliath crane. 

preparation and construction, so that no one stage 
should get too far ahead or impede that behind, was 
the contractor's first care; and things went forward 
at, on the whole, a very satisfactory rate. 

It is a testimony to the growth of engineering 
science that, whereas the old Admiralty Pier was 



HARBOR WORKS. 



369 



advanced only 91 feet per year, the recently-built 
extension, of equal section, has been put together at 
a yearly rate of 600 feet. In one particular month 
75 feet (= 601 blocks) were laid. We must remem- 
ber that, owing to the strong currents and the depth 
of the water, block-laying was possible for but three 
hours on each tide, and on rough days not at all. 




Fig. 195. — Diagram showing how blocks are keyed together 



THE ISLAIS^D BREAKWATER. 



To save time the contractors decided to build the 
island breakwater independently of any fixed con- 
nection with the shore. As a starting-point a great 
steel frame was set up in the sea at the east end 
of the site. Unfortunately, before it was sufficiently 
complete to be impregnable a great storm rose and 
entirely destroyed it, causing a delay of six months 

24 



HARBOR WORKS. 371 

for the removal of the debris. Eventually the gan- 
tries of the east arm were carried across the south- 
east mouth of the harbor and continued to the west 
end of the island breakwater. 

THE ADMIEALTY PIER EXTENSIOx/. 

This part of the scheme was completed first, but 
only slightly ahead of the much longer east arm, 
though it had a year's start. Being exposed to the 
full violence of the south-westerly gales, the work was 
much more hindered than that on the eastern break- 
water, which it partly protected; hence the difference 
in the rate of progress. An interesting feature to be 
noted in connection with the extension is the building 
of a temporary lighthouse on the frame of a Goliath, 
which was moved forwards with the cranes so that 
pilots might not drive vessels on to the new part of 
the arm. 

THE APEONS. 

Along the seaward side of all the breakwaters, and 
projecting 25 feet horizontally from the foot, is a 
solid " apron " of 13-ton blocks, S^/o feet thick, sunk 
more than half-way into the sea-bed. It was laid by 
powerful jib-cranes to protect the foundations from 



HARBOR WORKS. 373 

the undermining action of the waves. At the angles 
which the east arm makes with the shore are two 
large semicircular aprons shelving upwards with a 
gentle slope. These give the incoming waves a cir- 
cular motion which plays one off against another and 
robs them of their force. 

THE PPaXCE OF WALES PIEE. 

This is not part of the Admiralty works, and I 
refer to it only because its construction illustrates a 
second kind of pile-driving. For 1,200 feet it is an 
iron structure supported by hollow cast-iron piles, 
8 inches in diameter internally, driven in groups of 
three, except at the three ^' stiffening bays," where the 
number is increased to five. In all cases the two out- 
side piles were screwed into the chalk at a slight 
angle to the vertical — " straddled." The lower ends 
of these piles had sharp points, and carried steel 
blades arranged in a spiral fashion so as to form a 
gigantic screw. As '^ screwdriver " was employed a 
pair of hydraulic rams, terminating in racks, which 
engaged with a toothed wheel attached to the top of 
the pile. Every stroke of the rams gave the pile a 
quarter-turn. 



374 



HARBOR WORKS. 



For the centre piles, which have to bear the 
weight of a railroad track, a different method of 
sinking Avas employed — to wit, the pneumatic-caisson 
method, noticed in the chapter on Bridge Foundations. 

Cylinders, nearly 9 feet in diameter, were sunk 
in the chalk, the men working under pressure. The 
portion below the sea-bed was next filled with con- 
crete, capped with a large foundation stone, to which 




SAMD 



Fig. 198. — Section of breakwater to protect the Hodbarrow Iron Mines, 
Cumberland. 

the central pier was bolted. More concrete then filled 
the cylinder up to bed level, and the upper sections 
of the cylinder, used for sinking only, were removed 
for use with other piers. 

The National Harbor was begun in 1898 and 
finished in 1908. Ten winters of the fiercest storms 
availed nothing to injure the permanent work. At 
times the great rollers fiing themselves furiously on 



HARBOR WORKS. 



375 



the walls, and anon hurl 
parapets, but not a block is started; tliey have a 
better chance of leaving a mark on the white cliffs 
of Dover. It has been a straight fight between man 
and Mature, and man has won so far. Great Britain 
has gained one more refnge for her shipping — one 
more boom-protected roadstead for her floating forts 
should her naval strength be challenged. 

[Note, — The photographic views illustrating this chapter were kindly 
supplied by Messrs. S. Pearson and Son, Ltd.] 



Chapter XIX. 
TUNNELS AND TUNNELLING. 

Tunnelling difficult and risky work — Roman tunnels — Explosives 
and tiie powder drill — The shield principle — Classes of tunnel- 
ling — Mountain tunnels — Surveying — Transferring the centre 
line down a shaft — Operations underground — Methods of exca- 
vating — The Simplon Tunnel — The Brandt rock drill — Ventila- 
tion — Difficulties encountered and overcome — The headings meet 
■ — Accuracy of calculations — Other famous mountain tunnels — 
The Mont Cenis — The St. Gothard — The Arlberg — The cut-and- 
cover system — The longitudinal trench method — The transverse 
trench method. 

ATUE'IN'EL, being but a darksome bole made 
tbrougb tbe earth, cannot compare, as regards 
spectacular effect, with tbe big bridge or dam. Yet tbe 
driving of tunnels is a branch of engineering wbicb 
derives particular interest from tbe fact that it con- 
tinually places tbe engineer in difficulties surmount- 
able only by tli3 exercise of great ingenuity, yet in 
few cases unsurmounted. Tbe builder of a bridge 
works out bis calculations and assumes witb confidence 
that if certain conditions be fulfilled bis bridge will 
in time be an acccmplished fact. But what man can 



TUNNELS AND TUNNELLING. 377 

foresee the unpleasant surprises wliicli may await him 
as he burrows through a mountain or under a river 
bed? The work may prove quite straightforward 
from start to finish. On the other hand, it is at least 
equally probable that his patience and resource will 
be taxed to the utmost before his task is complete. 
His great foe is water, whether as the subterranean 
stream suddenly tapped by the blast, or mingled with 
sand and clay to form a treacherous stratum. Against 
the crushing of his timbering and masonry he must 
always be on guard. Add the discomforts and incon- 
venience of working in a very confined space to which 
there is access only through the passage-way already 
cut, where proper ventilation is obtained with difii- 
culty, and where the heat is often well-nigh intolerable. 
On the point of hardship, tunnel-driving, in common 
with mining and other underground work, is far 
ahead, or behind, as you please, most other branches 
of engineering. 

The Komans have left us some very fine examples 
of tunnel driving, the most notable being that made 
to drain Lake Fucino. It is 3% miles long, and has 
a section of 6 by 10 feet, and is said to have occupied 
B0,000 men for eleven years. In the absence of tools 
other than the pick and shovel, and of effective ven- 



378 TUNNELS AND TUNNELLING. 

tilation, only the unsparing use of slave labor could, 
we should imagine, have made such a feat possible. 
There were no Board of Trade inspectors around in 
those days. 

The invention of gunpowder carried the art of tun- 
nelling a long step forward, but it was not until the 
nineteenth century that engineers learnt how to pierce 
soft ground, requiring support as soon as excavated. 
The arrival of the railway made it necessary to learn 
this lesson. Then came the invention of the powder- 
drill, and very strong explosives, which enabled engi- 
neers to pierce Mont Cenis, the Arlberg, the St. 
Gothard, and the Simplon tunnels, and the introduc- 
tion of the ^' shield " principle by Sir Isambard 
Brunei (for use in water-bearing strata), since devel- 
oped to a high pitch of perfection. 

CLASSES OF TUNNELLING. 

For convenience' sake we may classify tunnels 
under three headings: — 

A. Tunnels through hills and mountains. 

B. Tunnels immediately bslow the surface of the 

ground — for example, the Kew York and Boston 
Subways, and the Metropolitan Railways in 
London and Paris. 



TUNNELS AND TUNNELLING. 



379 



C. Submarine tunnels, carried nnder a river, and very 

low-level tunnels such as the " Tube " railways 

in London. 

Though the methods distinctive of one class may 

be, and are, on occasion applied to another, we may 

associate the first class with a masonry lining built 

as fast as the excavation proceeds ; the second with 

the " cut and cover " system ; and the third with the 

shield forced forward through rock, gravel, or sand, 

to make a way for a continuous lining of iron or 

concrete. 

IMOUT^TAIN TUNNELS. 

When a hill or mountain has to be pierced, the 
engineer's first task is to 
gather as full information 
as possible about the na- 
ture of its interior. The 
services of experienced ge- 
ologists are employed, and 
actual samples of the strata 
through Avhich the tunnel 
has to pass are obtained by 
the diamond drill (Fig. 

199), a steel cylinder armed with low-grade diamonds 
at its lower or cutting edge, which as it rotates 




Fig. 199. — The head of a diamond 
drill, used for drilling deep 
test-holes in the earth. The 
black patches are diamonds set 
alternately on the outside and 
inside edges of the cutter. Their 
intense hardness enables the 
drill to grind its way through 
the toughest rock. The hollow 
core cut by the drill serves as 
a specimen of the strata pierced. 








TUNNELS AND TUNNELLING. 

pierces tliroiigli the hardest rock 
with ease. From time to time the 
drill is lifted and the core which it 
contains is extracted for exami- 
nation. 

SUEVEYING. 

The next process is to establish 
the exact centre line of the tunnel 
and the points from which observa- 
I o tions may be made periodically to 
keep the workmen on the correct 
line. In the case of a hill accessible 
-cs I at all parts the j^rocess is simple 
m I enough for a rectilinear tunnel. 
"" Si In Fig. 200 we see successive ob- 
^ I servation points, a^ b, c, d, e^ and f^ 
carried over the hill in a straight 
line by means of a theodolite, im- 
mediately above the path of the 
tunnel. For the Mont Cenis, St. 
Gothard, and Simplon tunnels the 
line was established by the indirect 
and much more complicated meth- 
od of survey triangulation. 



s ^ 



p t; 



■'.-■'.] -S 



^Ai'".'- ^ 



TUNNELS AND TUNNELLING. 381 

At each end of the tunnel-to-be two permanent 
pillars of masonry are set np. The theodolite is 
placed on the one farthest from the entrance ard 
sighted through a slit in a plate on the other on 
to an illuminated point in the tunnel at the '' face/' 
adjusted to be in line. As the tunnel advances 
another station is made in the tunnel, the theodolite 
is taken inside, sighted back to the original station, 
and turned vertically through half a circle so as to 
sight forward on the same line. As required, other 
stations are obtained in like manner. The utmost 
care must be taken to avoid errors, and that it is taken 
is proved by the wonderful accuracy with which the 
headings driven from opposite ends generally meet. 
In " Railroad Construction," the author, Mr. W. L. 
Webb, C.E., gives some interesting figures by way of 
illustration. The Musconetcong tunnel is about 5,0G0 
feet long. When the headings met the error in align- 
ment was found to be only half an inch, and the 
error in level only about one-sixth of an inch. In 
the Hoosac tunnel, 25,000 feet long, the error?, were 
even smaller. 

Where circumstances permit and render it advis- 
able, shafts are sunk at points on the central line 
of the tunnel, and headings driven from the bottom 



382 



TUNNELS AND TUNNELLING. 



in both directions. In the case illustrated bj Fig. 
200, six parties of workmen would be able to operate 
simultaneously. For very long tunnels through moun- 
tains towering thousands of feet overhead, shafts are 
out of the question, and the working faces are reduced 
to two in number. 

TEANSFEREING THE CENTRE LINE DOWN A SHAFT. 

The transference of the centre line down shafts is 
usually effected in the manner illustrated by Fig. 201. 



'^^^^^^^^^^^J^^Jj^^^^^s^^;?^;?^ 



•^^s^i^S^^^^^s^^:^^:^^^^^^^ 



5^^^?^^?:^^^=::'=^^?^^':;?^ 



^vss^ 



^?^^^s^^NN:^^^^^V?^^^^^v^^^ 



Fig. 201. — 



Two pillars, s s, are set up on the centre line and 
correctly marked. From a wire strung tightly be- 
tween the marks hang two long plumb lines, p p, with 



TUNNELS AND TUNNELLING. t^^t, 

the '^ bobs " steadied in pails of water or oil at the 
shaft bottom. These two plumb bobs serve as guides 
for carrying the centre line into both the headings. 

OPERATIOA^S UNDERGROUND. 

The method of excavating a tunnel depends upon 
the nature of the stratum penetrated. Where rock 
and other hard substances have to be dealt with, 
blasting is used to advance the ^^ face/' as the end of 
the tunnel is called, while pick and shovels suffice for 
soft materials. The section of the tunnel is usually 
arched, and a lining of masonry is built in wherever 
there is danger of the crushing in of the roof and 
sides, or of an irruption of water, the section being 
made extra large to allow room for the timbering 
inside which the masonry is built. The timbers are 
then pulled forward from between masonry and 
'^ ground," and the space filled in with stones, 
concrete, etc. 

There are several systems of excavating a tunnel to 
full section or '^ profile," of timbering, and of lining. 
In some systems a small pilot tunnel is usually run 
well ahead of the main work, either just under the 
line of the roof, in which case it is termed a heading, 
or just above the bottom, as a drift. The heading 



384 TUNNELS AND TUNNELLING. 

or drift is generally enlarged to the full section by 
gangs following behind the advance workers. In Fig. 
202 are six diagrams to illustrate the English, Amer- 
ican, Austrian, Belgian, French, and German systems, 
each of which is suited to special conditions and is 
employed only in the country of its origin. Th3 
numbers in each diagram indicate the order in which 
the slices of the section are removed. The English 
begins with a heading and a drift. The heading is 
then enlarged on both sides to complete the arch ; and 
extended downwards to meet the drift. Finally the 
tAvo side ledges are removed. In the American system 
one top heading and two bottom drifts are driven 
first and the central core is removed last. The Eng- 
lish, American, and Austrian systems are alike in 
excavating the full section before the masonry lining 
is commenced. In the French and Belgian the arch 
is built in at once and supported temporarily while 
excavation is completed and the side walls are added. 
The German system excavates for the side walls, 
builds them up, and then excavates for the arch, the 
solid core not being removed until the lining is prac- 
tically complete. This method has the disadvantage 
of compelling the excavators and masons to work in 
a very cramped space. An invert, or shallow inverted 



! I 

-- — — -—-—-, 

4 I 3 14 
s\ t 1 5 







Z ! 

; 
r 1 


3 


1 ^ 

j / 



Fig. 202. — Diagrams to show the English, American, Austrian, Belgian 
French, and German methods of enlarging a tunnel heading to full pre 
file. The numbers in each case indicate the order iu which the slices ar; 
removed. 

25 



386 TUNNELS AND TUNNELLING. 

arch, is built from wall to wall at the foot, where 
there is danger of the floor rising. 



THE SIMPLON TUNNEL^ 

as the longest tunnel in existence and one of the 
most difficult to make, deserves our special attention. 
It is a double tunnel with two parallel tunnels 56 
feet apart from centre to centre, one for each track. 
At present only one tunnel is finished and in use, 
but a gallery for the other was driven right through 




>- Wi""'"' -k 

Fig. 203. — Section of the Simplon Tunnel. The tunnel rises towards the centre 

to give drainage by gravitation. 

and connected at intervals with the first by cross head- 
ings to assist in the transportation of materials and 
the ' ventilation of the workings. Operations com- 
menced in ISTovember, 1898, and on January 25, 1906, 
the first train passed from Italy to Switzerland, with 
the King of Italy on board. The total cost of the 
completed tunnel and parallel gallery was £3,200,000, 
equivalent to £148 per lineal yard. 

To make holes in the face for the blasting charges 
th[: Brej.dt rock drill was employed. This machine 
consists mainly of a small double-cylinder hydraulic 



TUNNELS AND TUNNELLING. 387 

motor to rotate the drill proper^ and a hydraulic ram 
to press the drill hard against the rock. The drill is 
a hollow tube with three or four cutting teeth at the 
end. The water escaping from the engine passes 
down the centre of the drill and keeps the edge cool, 
besides scouring away the debris. In hard rock this 
drill will sink a hole 39 inches deep in about twenty 
minutes. 

Ten to twelve holes^ distributed over the face of 
the drift, having been made, the charges and fuses 
were inserted and the floor of the drift was covered 
with steel plates from which the splintered rock could 
be shovelled very easily. The workmen then with- 
drew all tools and other things liable to damage by 
the explosion, and lit the fuses. Immediately after 
the discharge, a valve was opened in the tunnel and 
five jets of water allowed to play on the rock, to lay 
the dust and clear the air. Then all the debris was 
shovelled into trucks and taken away to give room 
to the drilling machines, and the roof and side walls 
examined with picks to discover any loose and dan- 
gerous fragments. The rate of advance in a drift 
with a section of 59 square feet averaged about 18 
feet per day. On the Italian side, where the rock 
was hard and reliable ^' break-ups '' were made every 



388 



TUNNELS AND TUNNELLING. 



50 yards, and top-galleries driven from them in both 
directions. Eig. 204 shows a drift, c^ from which 




rV»H-^;"'4 :r^'i."'A<j'L ■A'-mX). 



^-. * J.<y,. *■ A A up 



m^^ ^'h 




vi^pig^^^wj) 



Fig. 204. — Cross and longitudinal sections of the Simplon Tunnel, showing a 
drift, c, and galleries or headings, A A, driven from the break-ups. 



break-ups have been made, and the galleries a a a 




driven right and left. 



The section (on the 
left) illustrates the 
of the 



timbering 



drift and galleries 
when first made, and 
the dotted lines the 
position of the in- 
I. termediate ground, 
broken 



Fig. 20.5. — Fully-developed timbering in tlie 
Simplon Tunnel, inside which the masonry 
lining is built. Polling, boards are placed 
between the timbering and the ground. 



In Fig. 205 



afterwards 
away, 

we have the fully- 
developed timbering 
of the tunnel, ready for the masonry. Steel '^ centres '^ 
were employed in the Simplon tunnel to support tht^ 



TUNNELS AND TUNNELLING. 389 

masonry arch during construction, as being more 
easily fixed and less damaged by frequent moving 
than wooden ones. 

VENTILATION. 

During the piercing of the St. Gothard in the 
seventies no fewer than 800 of the workmen died, 
mainly through the lack of proper ventilation in the 
galleries, and for means of keeping down the dust 
raised by the drills. In the Simplon Tunnel the 
arrangements for ventilation were excellent, twenty- 
five cubic feet of fresh air being supplied to the 
workmen for every one blown into the St. Gothard. 
The current of air was strong enough, we are told, 
to take a man's hat off; and as for the dust, it was 
kept down in the manner already described. It is 
satisfactory to be able to add that during the eight 
years of work on the Simplon, only 60 men lost their 
lives from all causes. 

In the heart of a mountain the temperature is 
much higher than that of the outside atmosphere, the 
heat increasing with the depth of the rock overhead. 
The maximum rock temperature — 133° Fahrenheit — 
in the Simplon Tunnel was encountered at a point 
about 7,000 feet below the summit of the mountain. 



390 TUNNELS AND TUNNELLING. 

This would have made things intolerable for the work- 
men had it not been tempered by huge quantities of 
cool air driven by fans through large pipes up to the 
face, and by water-sprays from pipes jacketed with 
charcoal, to prevent the water becoming heated dur- 
ing its passage up the tunnel. 

DIFFICULTIES ENCOUA^TEEED. 

Towards the end of 1901 the advanced gallery on 
the Italian side pierced a soft stratum, which crushed 
heavy timbering like so much matchwood. The way 
was cleared out again, and steel girders used in con- 
junction with wooden baulks 20 inches square. Even 
these yielded under the pressure. As a last resource the 
spaces between the beams were filled in with quick- 
setting concrete, which stood the strain while a very 
thick masonry lining was built, in spite of great dif- 
ficulties, inside the temporary support. 

As a result of this delay the Swiss got well ahead 
of their Italian rivals, and reached the centre point 
while the latter were still working their way uphill. 
In order to save time, they decided to drive the 
galleries downhill towards Italy to meet the other 
party. Then they unfortunately tapped some ex- 
'.remely hot springs, which ultimately compelled them 



TUNNELS AND TUNNELLING. 391 

to retire, after liaving fixed strong iron doors in the 
headings to hold back the water. 

The work was now definitely stopped on the Swiss 
side, and some people prophesied that the completion 
of the tnnnel was impossible. But the Italians 
pushed on, and at last listeners in the Swiss heading 
heard their drilling-machines at work, though half 
a mile of rock remained to be penetrated. Hopes 
revived. Then the Italians met the hot springs that 
had given the Swiss so much trouble, and in spite 
of all efforts to keep down the temperature by 
mixing cold water with the hot, work on the main 
tunnel had to be stopped. The engineers refused, 
however, to own themselves beaten, and continued 
the gallery of tunnel E'o. 2, with the object of 
getting round the flank of the springs, which, owing 
to the nature of the rock, they were fortunately able 
to accomplish. Then they drove a cross-cut to the 
line of tunnel ^Ko. 1, and worked back till they 
met the abandoned heading, and so were enabled to 
push on with greater vigor than ever. On February 
23, 1905, only 5 metres of rock remained unpierced; 
and next morning a blasting charge released the hot 
water imprisoned behind the iron doors in the Swiss 
heading. ^' The meetings of the headings at once 



TUNNELS AND TUNNELLING. 393 

proved the accuracy with which the work had been 
executed, but it lacked the fervor of delight usual on 
such occasions, as in this case it was a meeting of 
miners on the one side and hot water on the other. 
The last 245 metres of the gallery had occupied nearly 
six months in execution, owing to the unprecedented 
difficulties encountered.* 

The headings met with an error of but 8 inches 
laterally and S^/o inches vertically. The total length 
was found to be 31 inches less than had been 
anticipated. Considering that these errors are dis- 
tributed over 12J miles, their smallness is remarkable. 

By a noteworthy coincidence the Simplon Tunnel 
was opened almost exactly a hundred years after the 
completion of the military road over the Simplon 
Pass by j^apoleon — the first to promote the interests 
of peace and civilization, as the second was to make 
easier the passage of invading armies. 

Trains are hauled through the tunnel in 18 minutes 
( = 42 miles an hour) by electric locomotives. Tun- 
nel ]^o. 2 is being enlarged by Messrs. Brandt, Bran- 
dau and Co., the contractors for the first, and in due 
course the second track will be laid. 

* F. Fox on the Simplon Tunnel, "Proceedings of the Institution of 
Civil Engineers." 



394 TUNNELS AND TUNNELLING. 

OTHER FAMOUS MOUNTAIN TUNNELS. 

The Mount Cenis and St. Gothard tunnels are 
household words, and, though eclipsed in point of 
length by the Simplon, are in their way equally 
remarkable, as the obstacles to be overcome in the 
construction of all three were very similar. The 
Mount Cenis tunnel, like the St. Gothard, has a sec- 
tion large enough to take a double track. It measures 
7% miles from end to end, and took thirteen years of 
boring at an average daily rate of about 2^/2 yards. 
It was opened to traffic in 1871, and gives south 
France direct communication with Turin, Genoa, and 
Brindisi in Italy. 

The diversion of trade to this route put the Swiss 
on their mettle, and in 1869 they decided to pierce 
the Alps at the St. Gothard Pass, about 130 miles 
north-east of the Mont Cenis tunnel, and so obtain 
a quick route to Italy. The Swiss, German, and 
Italian governments, all of which would benefit, sub- 
scribed the necessary money (£2,327,000) between 
them, and work was begun in 1871 on a tunnel 9 J 
miles long. Here for the first time a locomotive 
driven by compressed air was used to remove earth 
and broken rock from tunnel headings, and the type 



TUNNELS AND TUNNELLING. 



395 



of air power-drills employed was a great improve- 
ment on those used for boring the Mont Cenis, 
though inferior to the Brandt hydraulic drill. But 
the ventilation left much to be desired, and the heat 
in the tunnel was such as to kill many horses, and, 
as we have already noticed, cause great mortality 
among the workmen. The work occupied eleven 
years, the tunnel being opened on June 1, 1882. 
Some remarkable engineering feats had meanwhile 
been done on the lines approaching the tunnel at both 
ends, notably the boring of thirty-three tunnels, eight 
of them of the helicoidal, or corkscrew type, a mile 
long each. 

The success of the St. Gothard Tunnel roused the 
emulation of the Austrians, who greatly desired an 
independent route to Paris, via Basle, through the 
Arlberg in the Austrian Tyrol, the watershed sep- 
arating the basins of the Rhine and Danube. The 
railway pushed from Innsbruck to the Rhine is a 
fine piece of work throughout, and its most striking 
feature is the Arlberg Tunnel, 6% miles in length, 
begun in 1880, and completed ^yq years later. The 
Brandt hydraulic drill here proved its superiority for 
tunnel work over the air-driven percussion-drills used 
in the Cenis and St. Gothard bores, and the expedi- 



396 



TUNNELS AND TUNNELLING. 



ency of spraying the working face Avitli fine water 
jets immediately after an explosion was established. 
In fact, the engineers learned several valuable lessons 
in tunnel-driving, which they were able to turn to 
account in the Simplon Tunnel operations. 




Fig. 207. — A Thompson electric excavator, used in " tube " tunnels. The 
front arm round which the budgets pass can be moved in all directions, 
so as to reach the whole of the face. 

The Simplon, the most recently completed of the 
Alpine tunnels, lies between the Mont Cenis and the 
St. Gothard, with both of which it competes suc- 
cessfully, thanks to its gentle gradients and its less 
altitude above the sea. It will in turn soon be 
threatened, as the French, smarting under the loss 
of traffic over the Mont Cenis route, have opened 
negotiations with the Italian government for a rail- 



TUNNELS AND TUNNELLING. 397 

way to join Aosta in Italy with Chamonix in France, 
passing right under Mont Blanc in a tunnel 11-g- 
miles long. This railway would become the high- 
road for traffic between England and Brindisi, via 
the northern French ports and Geneva, and divert 
a great deal of that which now uses the Swiss lines 
and the Simplon and St. Gothard tunnels. 

So the peaceful battle goes on between nation and 
nation, and we may expect to see the Alps pierced 
again and again, and still again, in the desire to reach 
Italy and her Mediterranean ports. 

A project which threatens to eclipse all existing 
tunnels is one for driving a canal tunnel through the 
high ground between the Rhone and Marseilles. The 
tunnel is to be 4% miles long, 70 feet wide — to allow 
two large barges to pass one another at any point — 
and 50 feet high. The amount of material to be 
removed would greatly exceed that shifted in any 
tunnelling feat yet accomplished. 

THE '' CUT AND COVER '' SYSTEM 

of tunnelling is used mainly for shallow underground 
railways in towns, and for aqueducts and sewers. 
Where traffic will not be impeded, a single trench 
of the required width is excavated, the tunnel built 



398 TUNNELS AND TUNNELLING. 

in it length by length, and the surface made good 
bj ramming do^m. earth on the arch. In busy streets 
this simple method is impracticable, and it becomes 
necessary to carry out the work in some manner which 
shall cause as little inconvenience to the public as 
possible. 

One of two alternative methods, or a combination 
of both is generally used under such conditions. We 
may notice them briefly. 

The Longitudinal Trench Method. — Two narrow 
parallel trenches are dug, one on each side of the 
road, for the side walls, which are built in them up 
to the commencement of the arch. The surface is 
then removed in strips to the centre line of the road, 
and half the arch built and covered; next, the other 
half is cleared, and the remainder of the strip of arch 
built and covered in. One-half of the road is thus 
kept open always for traffic. Finally, the core 
enclosed by the walls and arch is excavated in the 
usual manner from either end of the tunnel and 
through shafts left at intervals for the purpose. In 
some cases the arch is built across at once in strips, the 
road being closed during the least busy hours of the 
twenty-four. 

The Transverse Trench Method. — In this the road 



TUNNELS AND TUNNELLING. 



399 



is excavated to full depth across the street in slices 
during the night, and covered over with beams and 
stont planks to carry the day traffic. In the day- 
time the masons build up the masonry under this 
temporary roof. This method was largely employed 
for the Boston Subway and the ^ew York Rapid 
Transit Subway. In very busy streets, where the 
traffic was heavy at night as well as by day, all the 
work had to be done from below. Small drifts were 
driven for the lower parts of the side walls, whereon 
the workmen laid rails to carry a movable shield, to 
support the roadway while the earth was removed and 
the masonry laid. The mention of a shield prepares 
the way for our next chapter. 



Chapter XX. 
SUBMARINE TUNNELS. 

The Severn tunnel — The shield system of tunnelling — Construction 
of the shield — The front-end, bodj^, and tail — Shields with air- 
locks — The Rotherhithe tunnel — Sinking the shafts — Driving a 
"pilot" tunnel — The big shield at work — Advancing the shield 
— Guiding the shield — Accuracy with which the shield is steered 
— Some instances — Fighting water — Securing a tunnel with 
piles — Big tunnelling projects — The Harlem River tunnel — 
Bviilding the caisson — Constructing the tunnel under the caisson 
— ^Another method tried successfully — The Detroit River tunnel 
— A double-barrelled tube sunk by sections — How it was done 
— Connecting up the sections — Covering the sections with con- 
crete. 

THE majority of submarine tminels have been 
driven under a river at a point where the 
influence of tides is felt, hence their name. There 
are nine timnels under the Thames in the London 
tidal reaches, and in Xew York a dozen or more 
tunnels under the Hudson and East Rivers connect 
Manhattan Island with 'New Jersey and Long Island. 
In submarine tunnelling the engineer has most to 
fear from the inroad? of water from the river above, 



SUBMARINE TUNNELS. 401 

which is inexhaustible, and cannot therefore be run 
dry like many a spring tapped in the heart of a 
mountain. The strata through which he has to bur- 
row are often silt, clay, gravel, and other treacherous 
materials. He cannot employ drainage by gravita- 
tion, as the submarine tunnel falls toAvards the centre 
(see Fig. 211), and such water as does find its way 
in must be removed by pumping. 

The Severn Tunnel, driven under the river of that 
name in the years 1873-85, is a notable instance of 
a submarine tunnel excavated, timbered, and lined 
in the same way as the Simplon and other mountain 
tunnels. In spite of the fact that the engineers kept 
well below the river bed they were greatly hampered 
by water, which on more than one occasion completely 
drowned the headings, and was checked only with 
the help of an expert diver. 

As the length of a tunnel must be increased with 
its dip, gradients being equal, its roof is kept as near 
the river bottom as possible, and the engineer has 
generally to pierce a water-bearing stratum at one or 
more points. The difficulty of preventing the caving 
of the ground and the inflow of water led the famous 
Isambard Brunei to introduce 



26 



SUBMARINE TUNNELS. 403 



THE SHIELD SYSTEM OF TUNNELLING 

for the construction of the first Thames Tunnel 



opened in 1843. This system has since been much 
improved by Greathead and other engineers, and is 
generally used for the construction of deep-level tun- 
nels such as the London '^ tubes/' as well as for sub- 
marine. The lining of such tunnels is of iron rings, 
built up in segments, sometimes reinforced inside with 
concrete. 

CONSTRUCTION OF THE SHIELD. 

Tunnelling shields are of several types, adapted 
to meet different conditions. The simplest form is 
a cylinder of steel plates, absolutely smooth on the 
outside, its ^^ front end " furnished with knives set 
close together round the edge; or the plates of the 
edge itself are made to form a huge circular cutter 
of wedge-like section (see Tig. 208). Some feet 
behind the cutting edge is a stout diaphragm, or bulk- 
head, to prevent the cylinder being distorted by pres- 
sure. The diaphragm has a large hole or holes in 
it, through which the stuff dug from the working face 
is removed. In some cases the diaphragm is replaced 
by strong girders, and, where the shield is very large, 



SUBMARINE TUNNELS. 405 

the front end is divided np into compartments by 
vertical and horizontal partitions, so that the men 
may attack the face at several levels simultaneonsly. 
(Fig. 209 is an example of a shield thus divided 
into six compartments.) 

The hody of the shield contains a nnmber of 
hydraulic jacks arranged at regular intervals inside 
the lining (see Fig. 209), their cylinder ends attached 
to a stout ring, and their rams all pointing towards 
the rear end. Here, too, are stationed the pumps, 
motors, and machinery for getting the segments of 
the rings into place. 

The rear end, or tail, is at least as long as two 
rings of lining, so that it may rest on the last com- 
pleted ring, and support the earth while another ring 
is added. 

Where unstable and treacherous materials have to 
be pierced and where water is present, a shield of 
the type shown in Fig. 210 is used, in conjunction 
with compressed air. The front-end is shut off from 
the tail by a double diaphragm fitted with doors, so 
as to form a number of air-locks through which men 
and the excavated debris pass. On every floor of the 
shield is a safety-chamber, with an air-tight steel 
curtain, it, extending downwards from the floor above 



4o6 



SUBMARINE TUNNELS. 



so as to partly separate it from the face. If water 

suddenly invades tlie shield the workmen take refii.ce 

behind these curtain; _^^___^^ 

— above the bottom "'"^"^ ^"^^ \^ 

of which the water cannot 

rise — and make their way 

out through the air-locks. 

In some tunnels driven 
by compressed air, the 
shields are open, and the 
air is retained by a bulk- 
head built some dis- 
tance away in the 
tunnel, safety-cham- 
bers beino; provided 
at intervals between it and the face. The reader must 
understand that no two tunnels are driven under ex- 
actly the same conditions and that therefore engineers 
have to be constantly adopting new expedients to meet 
novel difficulties. 

Submarine railway tunnels and '^ tubes " are made 
in pairs, one for each track. Vehicle and footway 
tunnels, such as the Blackwall and Rotherhith? 
under the Thames, are single tubes of very large 
diameter. 




WW^^y^^^^mmn 



Fig. 210. — Section of a shield witli air- 
locks, for use in water-logged strata. At 
the bottom is seen a man taking refuge in 
a safety-chamber from an inrush of water. 



SUBMARINE TUNNELS. 



407 



V- :^ 



THE KOTHEEI-IITHE TUNNEE 

has a total length, including approaches, 
of 1;J miles, and an outside diameter of 
30 feet. It connects Shadwell on the 
north hank with Rotherhithe on the Sur- 
rey side. 

Of the total length 3,580 feet were 
shield-driven and lined with iron rings 
2 inches thick; 1,140 feet were con- 
structed on the " cut and cover '' prin- 
ciple, and the balance of the work is 
represented by open approaches. Re- 
ferring to Fig. 211, which shows the 
tunnel in section, you will notice that 
there are four shafts — s, s^, s^, s^. Be- 
tween shafts 3 and 4 the tunnel runs on 
a curve of 800-foot radius. Between 
shafts 2 and 3, and between 2 and 1, it 
is straight, there being a slight angle in 
the line at shaft 2. Much of the land 
tunnelling was done under houses and 
other buildings, including the South 
Metropolitan gas works, but without 
causing any disturbance of the ground 
or of the foundations above. 



4o8 SUBMARINE TUNNELS. ■ 

Operations began with the sinking of the four 
shafts, the two deeper ones of which were located 
as near the river as possible. Each shaft was sunk 
by a circular vertical steel caisson, having two con- 
centric shells, 60 and 50 feet in diameter, braced 
together. At the bottom the inner shell was tapered 
outwards to join the outer and form a cutting edge. 

Thirteen feet above this edge was a permanent 
floor of steel plates attached to cross girders, and 
above the level of the floor were two circular open- 
ings in the caisson, 32 feet across, one on each side, 
on the line of the tunnel. Dilring the sinking of the 
shaft these were closed by timber bulkheads of the 
same curve as the outer shell. 

Men working under the floor excavated a path for 
the caisson, wdiich was added to above as the cutting 
edge, impelled by the weight of the steel mass and of 
the concrete filled in between the two shells, bit its 
way downward. When the full depth had been 
attained, the cavity below the floor was made solid 
with the same material. 

As soon as shaft l^o. 3 was complete and a 
temporary air-tight floor had been constructed above 
the caisson openings, so that compressed air might be 
used, a shield, 11 feet 8i/i> inches in diameter, was 



SUBMARINE TUNNELS. 409 

erected at the bottom^ and started off on a joiirnev 
under the river, to cut a ^' pilot " tunnel, from the 
driving of which information about the nature of the 
ground could be learned. This shield made its way 
without much difficulty to within 50 yards of shaft 
Xo. 2, when it was stopped. Progress was greatly 
expedited by the use of an excavating machine 
attached to the front of the shield — a wheel revolving 
across the face of the heading three times a minute, 
scooping out deep grooves and delivering the material 
into cars by endless conveyors. This machine is the 
invention of the contractors, Messrs. Price and 
Keeves. Another type of digger — the " Thompson " 
is shown in Fig. 207. It was used with success in 
the central London '' tubes." 

While this small tunnel was being driven and lined, 
a huge shield 30 feet 8 inches across and 18 feet 
long had been erected in shaft !N"o. 3. Horizontal 
and vertical partitions divided the front into sixteen 
compartments. Por advancing it, forty hydraulic 
jacks with 9-inch (diameter) rams were installed, able 
to give a 5,000-ton shove when all- worked together. 
Prom the rear end projected a stage 50 feet long, 
carrying pumps, lifting tackle, and other mechanism. 
This monster now made its way out through the 



SUBMARINE TUNNELS. 411 

southerly opening in the caisson, and followed the 
track of its smaller predecessor running on the same 
centre. 

To give the shield a piish-ofF, temporary rings are 
erected in the shaft and kept there until several rings 
of permanent lining have been placed. The latter 
rings, each weighing 20 tons, are compounded of six- 
teen segments, with flanges 14 inches deep on all 
four edges, by which they are attached to one another 
and to the segments of the two adjacent rings. To 
lift them into position powerful presses were em- 
ployed. 

Every segment contained a hole tapped for a 
screw plug, through which liquid cement was force J 
to fill up the small annular space between the lining 
and the ground, due to the shield being of somewhat 
larger diameter than the lining. 

The process of advancing a shield is as follows. 
While the last ring is being built up, the rams of the 
hydraulic jacks are drawn fully into their cylinders, 
so as to be out of the way. The ring finished, high 
pressure water is turned into the jacks, and all the 
rams push simultaneously against the foremost flange 
of the lining, driving the cutting edge some distance 
into the unbroken ground. The workmen then attack 



SUBMARINE TUNNELS. 413 

the face except near the edge; and when a vertical 
slice has been removed, the jacks give another push, 
and so on, until the rams have made their full stroke. 
Then they are withdrawn, and the next ring is 
erected. 

GUIDING THE SHIELD. 

The jacks have to steer the shield as well as push 
it. In rounding a curve to the right, the left-hand 
jacks are made to do more work than those on the 
right at each advance, and conversely, if the curve 
bears to the left. To get a down-grade line the top 
jacks do most of the pushing; for an up-grade, the 
floor jacks, though when the line has once been struck 
all jacks take an equal share. 

Figs. 214 and 215 serve to explain how a shield 
is guided laterally and vertically. Of course, all cal- 
culations are based upon careful observations made 
with the theodolite, and checked frequently to prevent 
errors creeping in, as submarine tunnels driven from 
two or more points by shields moving towards one 
another should meet absolutely accurately. 

To take lateral guidance round a curve first. Two 
file marks are made on the lining (Fig. 214), on an 
imaginary line drawn from the centre of the circle 
of which the curve is a part. Two rods^ n n^ are 



414 



SUBMARINE TUNNELS. 




Fig. 214. — Diagram to explain how a 
shield is guided round a curve by meas- 
uring-rods. 



applied horizontally to the sides of the tunnel, one 
end fixed at the file marks, the other end merely sup- 
ported. On these rods marks are made at distances 

from the file marks 
proportionate to the 
length of the radii of 
the inner and outer 
curves of the sides of 
the tunnel ; thus in the 
example given (Fig. 
214) the distances would be in the proportion of 26 
to 29. 

Upper rods, m m^ marked to feet and inches, are 
laid on i^ i^, and their forward ends kept pressed hard 
up against the shield when the jacks are moving it 
forward. By comparing the readings on the upper 
rods relatively to the marks on the lower rods, the 
workmen are able to regulate the advance and main- 
tain the curve. 

To guide the shield horizontally or on the slope 
an arm, s (Fig. 215), of a certain length is fixed to 
the diaphragm. From this hangs a plumb-line. Dur- 
ing an advance a graduated ^^ plumb-stick " -l, is held 
horizontal by a workman against the shield. If the 
drive is to be perfectly horizontal, the plumb line 



SUBMARINE TUNNELS. 



415 




£ 



Fig. 215. — Section of a shield, stiowing 
measuring-rods, n^ m, and plumb-line. 



must lie opposite the zero mark on the plumh-stick; 
if upwards^ outside the mark; if downwards, inside 
the mark, by an amount carefully calculated by the 
engineer in charge to give the requisite gradient. 

Erom time to time he 
leaves written instruc- 
tions of the following kind 
for the foreman : '^ Lead, 
one inch right/^ " Plumb, 
half-inch i/p." At every 
few rings observations of 
* level and right or left 

deflection, are taken by 
instruments. 

The accuracy with which these submarine tunnels 
are driven appears all the more extraordinary when 
we consider that they are not rectilinear, and often 
include some awkward curves. Sir Douglas Fox, in 
a speech at the Institution of Civil Engineers, gave 
an interesting example of exactness in calculation. 
He said: " In the case of the 'Mersey Tunnel it was 
impossible to place the shafts on the line of the 
tunnel, and there were curved headings leading from 
one of the shafts to the tunnel. Consequently the 
setting out was complicated. It was rendered still 



4i6 



SUBMARINE TUNNELS. 



more difficult by the fact that the lines were set out 
in a drainage heading which was a continuous shower- 
bath. It was exceedingly difficult even to walk along 
the heading, and still harder to perform any delicate 

operation in it. In 
that case, when the 
two headings were 
about to meet, it was 
decided that the may- 
ors of the two towns 
should come and 
shake hands in the 
middle. He ven- 
tured to suggest to 
the resident engi- 
neer that a bore hole should be put in [from head- 
ing to heading] before the mayors came, at which 
he was offended, saying that it was unnecessary, as 
he was quite certain where he was. However, Sir 
James Brunlees and himself insisted upon having it, 
with the result that a bore-hole was put through from 
one side in the centre line, and the end of the bore- 
hole struck the centre line on the other side." On one 
of the London tubes where there were six meetings, 
five of them were less than % inch out ! 




Fig. 216. — Section of station tunnel, Cen- 
tral London Railway, showing two train 
tubes. 



SUBMARINE TUNNELS. 



417 



On very sharp curves the lining rings have to be 
tapered towards the inside; en gentle curves the 
V-shaped spaces between parallel rings are carefully 
packed and made watertight with metal, cement, wood, 
or some other material. 




Fig, 217.— 

To return to the Rotherhithe Tunnel. The big 

shield eventually found its way to shaft 'No. 2, 

through which it passed on an upward grade till 

shaft No. 1 was reached. Meanwhile a second shield 

of extra solid design had been erected in shaft 3, 

and driven north-east on a curve to shaft 4. It 

remained to line the iron tube with a thick coating 
27 



4i8 SUBMARINE TUNNELS. 

of cement, extending 4 inches beyond the flanges^ 
and face it with white glazed tiles; also to build a 
continiions arch along the bottom of the tunnel, to 
carry the road and sidewalks, as well as serve as a 
subway for electric and w^ater mains. The central 
carriage way is 16 feet wide, and each of the side- 
walks 4 feet 8% inches wide. From end to end the 
tunnel is lighted by three rows of electric lamps. 

For this great task were required: iron, 27,000 
tons; steel, 4,000 tons; cement, 30,000 tons; besides 
5,000,000 bricks, 40,000 square yards of asphalt, and 
100,000 cubic yards of cement concrete. 

FIGHTING WATEK. 

The making of the sub-river portion of the 
Rotherhithe Tunnel was not accompanied by any 
very great difficulties. In the case of the Blackwall 
Tunnel, the river section of the Baker Street — Water- 
loo tubes, and several of the ^N'ew York tunnels, the 
presence of water required the greatest care in 
excavation, it being a matter of some delicacy to so 
balance the air pressure tliat on the one hand the 
water might be kept at bay, and on the other there 
might not be a ^' blow-out " of river-bed. Such a 
blow-out on the Hudson River tunnel resulted in the 



SUBMARINE TUNNELS. 419 

loss of twenty lives and the abandonment of the work 
for several years. To prevent disasters of this kind 
it is sometimes necessary to dump large quantities 
of clay on the bed of the river above the line of the 
tunnelj the clay being removed after it has served 
its purpose. For dealing with very soft material 
the front of the shield is protected by a bulkhead 
near the face, with a number of small openings in it, 
which can be closed by shutters, in some instances 
so small that the workmen have to do the excavating 
with their hands. 

As a tunnel weighs less than the volume of water 
which it displaces, there is a tendency for it to float 
in mud and silt. Some of the ]N^ew York tunnels 
are secured against any vertical movement by huge 
piles driven down by hydraulic power to firm 
ground through holes cut in the bottom, and attached 
securely to the lining. 

Submarine tunnelling has been so perfected that 
engineers seem able to cope successfully with all 
conditions. They are prepared, if called upon, to 
tunnel under the Straits of Dover and make railway 
tubes from Scotland to Ireland. The project has 
even been seriously mooted of burrowing under the 
Behring Straits, so that one might journey by train 



420 



SUBMARINE TUNNELS. 



from E"ew York to London, assuming the Channel 
Tnnnel to be already in existence. Considering the 




Fig. 218. — Exploring with boring machine, Pennsjlvauia Railway Tunnel, 

New York. 

(Photo, Pemisylvania Railroad Co.) 

magnitude of past victories of engineering science, 
the chief difficulties in the way of any one of these 



I 



SUBMARINE TUNNELS. 421 

schemes appear to be financial and political rather 
than physical; and one should think twice before 
classing them with '^ wild-cat " propositions. The 
^' im]30ssible " of to-day is the matter-of-fact achieve- 
ment of to-morrow. 

THE HAELEM EIVEE TUNNEL. 

Having dealt at some length with the '^ shield " 
method of tunnel boring, we may turn our attention 
to a different system of making a tunnel. A tunnel 
destined to carry the double tracks of the new Rapid 
Transit Subway has been taken under the Harlem 
Eiver, New York, in a novel manner worthy of 
notice. 

Owing to the river bed being of so soft and treach- 
erous a nature that the driving of a tunnel through 
it at the necessary level would have been attended 
by the greatest risks, the engineers adopted a plan 
of their own. This was to construct a watertight 
gallery in the river bed, and to establish the double- 
track tunnel inside it. How they carried out their 
purpose is explained by Figs. 219, 220, and 221. 

First a trench w^as scooped in the river bed on the 
line of the tunneL Piles, p p (Fig. 219), were then 
driven down on each side of the trench to carry 



422 



SUBMARINE TUNNELS. 



working platforms. The workmen then drove be- 
tween the platforms several parallel rows of shorter 
piles p^ p^, those on the outside, s p, s p, touching one 
another so as to form continuous watertight walls of 
s/iee Spiling, kept in line by horizontal beams bolted 




Fig. 219. — Diagram to show section of caisson under wliich part of the 
Harlem River Tunnel -was built. 



along the outside near the top, and connected by 
cross trusses. Driving the sheet-piling was no easy 
matter, as lumps of rock occasionally obstructed the 
points, and blasting had to be resorted to before the 
pile could be sent home. Moreover, on account of 



SUBMARINE TUNNELS. 423 

the size of tlie piles, each compounded of three beams 
12 bv 12 inches in section, all tono'ned and 2:rooved 
to interlock with the next pile, it was necessary to 
prepare holes for them with " pilot '' piles of steel 
carrying pipes that squirted high-j^ressnre water out 
at the tips, and quickly ate a way down through the 
sand. 

When the sheet-piling had been properly aligned 
by divers, a circular saw suspended from a moving 
platform spanning the trench was employed to cut 
off the heads of the piles at a certain level, the saw 
being gradually raised or depressed as it moved along, 
so that the exact grade of the tunnel should be 
observed. 

Carpenters now busied themselves in the prepara- 
tion of a massive timber roof built up of several 
layers of baulks and planks. This was floated over 
the short piles in sections, and sunk with its edges 
resting on the sheet-piling, to which it was attached 
by angle irons. All joints having been caulked, and 
bulkheads built at the ends, mud was heaped over 
the roof, and pumps extracted the water. In order 
to admit workmen and materials, shafts were con- 
structed from the roof to the platforms, their upjoer 
ends terminating in air-locks, as a moderate extra 



424 



SUBMARINE TUNNELS. 



air-pressure was needed to keep the chamber clear 
of water. 

Under cover of the wooden walls and roof the 
workmen excavated a rectangular space somewhat 
deeper than the tunnel. When the floor .had been 
levelled, a thick bed of concreting was laid among 
the piles (p^ p^, Fig. 219), which were then cut off 
flush vrith the concrete and spiked to get a grip of a 
fi^ second layer of con- 



___| _ Crete spread over the 




~= first. Segments of the 

cast-iron lining were 

introduced through 

ff^ the shafts and bolted 



together in position on 

the concrete, which, as 

soon as the metal-work 

J permitted, was brought 

' up and over the tubes, 



1 



Fig. 220. — Harlem River Tunnel, 
completed inside caisson. 



Section 



the sheet-piling shap- 
ing the sides of the 
mass. Fig. 220 shows a section of tunnel at this stage. 
The removal of the roof, the cutting off of the sheet-pil- 
ing heads, and the dismantling of the side platforms, 
so as to leave the waterway clear, completed the worl:. 



SUBMARINE TUNNELS. 425 

V, lien the tunnel had been partly constructed the 
engineers decided to modify their system in a manner 
which is explained by Fig. 221. For the tall piling 
of Fig. 219 was substituted shorter piling which 
reached only to the central horizontal line of the 
tunnel, and the place of a solid wooden roof was 
taken by sections of the top half of the tunnel itself, 
previously finished and lowered into position on 
the piles. 

For the preparation of the roof a pontoon was 
made between the working platforms. Inside this 
the segments of the iron tunnel rings were assembled 
and bolted together, until the upper half of the 
^'double barrel" had been formed. A wooden floor 
was attached to the bottom, and a wooden bulkhead 
to each of the four semicircular ends, so as to form 
tAvo watertight chambers. These were covered with 
concrete to the shape shown in Fig. 221. The 
pontoon was then sunk in the w^ater till the section 
floated, and one end of it was removed so that it 
could be withdrawn from under the section, which 
had previously been made fast to lifting tackle rest- 
ing on the platforms. 

Valves having been opened, the section filled 
slowly and sank on the piles, to which divers ad- 



426 



SUBMARINE TUNNELS. 



justed the edges exactly. The divers/ entering the 
section, attached it to that on the shore side, and 
screwed bolts through, the edges of the iron-work 
into the sheet-piling on which they rested. 




Fig. 221. — Second method used for the Harlem River Tunnel. The top half 
of t;.e tunnel was lowered on to sheet piling, to form a water-tight cham- 
ber, in which the lower half was built. 

After all joints had been made watertight the 
mud was piled over the section to keep it down, and 
the work of excavating for the lower half of the 
tunnel proceeded under compressed air, as in the 
original method. The half rings were attached to 
their corresponding ujDper halves, and the space 



SUBMARINE TUNNELS. 427 

between the outside, the iron-work, and the sheet- 
piling was filled with concrete to complete the pro- 
tecting and strengthening envelope. In Fig. 221 the 
right half of the section shows a completed tnbe; 
the left half, the formation of the roof when first 
made fast to the sheet-piling. Access for materials 
and egress for the excavated mud, etc., was, of course, 
afforded by breaking dow^n the end bulkheads of 
each section and establishing direct communication 
"vith the shore. 

This method has proved so satisfactory and ex- 
peditious that we may expect to see it widely 
employed in the future where the natural conditions 
are suitable. It is not accompanied by the perils of 
a ^^ blow out,'' which are the nightmare of workers 
engaged on the driving of a shield through a treacher- 
ous stratum. It has the further advantage that it 
permits work to be carried on at several points simul- 
taneously, instead of at two only, which is the 
maximum number possible in a tunnel bored under a 
river bed, unless expensive shafts be constructed in 
the river itself. While dredging is done at one place, 
pile-driving proceeds at another, section-forming at a 
third, and section- sinking and fixing at a fourth, so 
that little time is lost. 



428 SUBMARINE TUNNELS. 



THE DETROIT RIVEE TUNNEL. 

The waters of Lakes Superior, Michigan, and 
Huron pass into Lake Erie through the Detroit River, 
which for about one hundred miles forms part of the 
boundary line between the United States and Canada. 
On the western bank, not far from Lake Erie, is the 
City of Detroit, and opposite to it, almost at the end 
of the long Ontario peninsula, stands the Canadian 
town of Windsor. A good map will show you that 
several railroads converge on Detroit, which is one of 
the most important centres of the railroad systems 
connecting Chicago and the west with New York, 
the New England States, and Eastern Canada. 

Hitherto the passage of the Detroit River has 
necessitated the use of great ferry steamers, sufficiently 
capacious to accommodate a complete express train. 
These ferry boats ply in all seasons, crashing through 
the winter ice-floes when they accumulate. But under 
the best of summer conditions the transference of 
train from quay to boat and from boat to quay means 
the loss of at least half an hour in the case of an 
express, and some hours when a long and heavy 
^' freight" has to be handled. In addition to the 



SUBMARINE TUNNELS. 429 

expense of delays — for time is money on the railroad 
as elsewhere — comes that of maintaining the ferry 
boats and. keeping the crossing clear in winter; so 
that, in view of the rapidly increasing traffic on the 
Detroit routes, it became imperative to remove the 
obstruction in one way or another. 

The erection of a bridge being put out of court by 
the boat traffic between the lakes, a siib-river timnel 
was the alternative. Mr. Henry B. Ledyard, presi- 
dent of the Michigan Central, prevailed upon his 
board of directors to authorize a tunnel, the designing 
of which occupied many months prior to the summer 
of 1906, when the final plans were adopted. 

These plans provided for a double-barrelled tunnel 
of steel tubes lined with concrete, through w^hich trains 
would be operated by electricity. The total cost of 
the undertaking was estimated at $8,000,000, a huge 
sum indeed, but moderate in view of the great 
advantages that the tunnel would confer on the rail- 
roads making use of it. 

We have already seen how tunnels are driven 
through rock and through the silt and clays of a river 
bed. We have noticed also the method of construct- 
ing the Harlem River Tunnel. ■ This last method 
approaches most nearly to that adopted for the tunnel 



430 SUBMARINE TUNNELS. 

now under consideration ; but there is so great a 
difference between the two that the Detroit River 
Tunnel, for the scheming of which Mr. W. J. Wilgus 
was chiefly responsible, affords a gigantic novelty in 
engineering. 

The project was briefly this: to scoop a trench 45 
feet deep and 40 feet wide at the bottom across the 
bed of the river from Detroit to Windsor; in this 
to lay lengths of huge double tubing, bolt them end 
to end, and cover them with concrete, clay, and 
stones, and to join up the extremities of the tubes 
to tunnels and cuts rising at a gentle gradient to the 
general level of the adjacent country. 

The actual work was done as follows. First, great 
dredgers scooped out the trench. Floating pile-drivers 
followed driving piles down till their heads were level 
Avith the bottom of the trench, and at such distances 
apart that the tubes should rest upon them at the 
desired points. 

The tubes, of stout steel plate, are each 23 feet in 
diameter, and built up in 260-foot sections, the two 
tubes of each section being connected and surrounded 
by vertical cross diagrams at intervals of 11% feet. 
The Great Lakes Engineering Comj)any were re- 
sponsible for the steelwork. 



SUBMARINE TUNNELS. 



431 



Each section, when complete, had its ends plugged 
with timber to make it watertight, was launched, 
towed down the river 48 miles to the scene of opera- 




FiG. 222.— Section of the Detroit River Tunnel ready for sinking into trench 
in the river bed. 

tions, and brought to rest exactly over its final posi- 
tion in the river bed. Water was then admitted 
gradually, and the section sank slowly, its alignment 
being kept correct by means of the temporary vertical 



432 SUBMARINE TUNNELS. 

masts attacliecl to each end. Four cylindrical floats, 
10 feet in diameter bv 60 in length, assisted the tubes 
to settle on an even keel, with the diaphragms resting 
on or over the beams of the piling below. (Figs. 223 
and 224.) 

Divers now descend 80 feet or so into the water, 
examine the supports carefully, and where necessary 
place packings between piles and diaphragms. Their 
next duty is to connect the newly-sunk section, which 
we will call a, up to that already in position, b. To 
effect this a loose sleeve or ring at the end of a is 
slipped over the end of b, and the flange of the sleeve 
is screwed up against a flange on b — a thick rubbe- 
ring having been first inserted, so as to make a water^ 
tight joint. An internal flange at the rear end of the 
sleeve is simultaneously brought up against a second 
rubber ring on the inside of an external flange at the 
extreme end of a. Between the sleeve and b there is 
thus enclosed an annular space 18 inches long and 
3 inches deep. The water is pumped out of this, and 
when the joints have been tested to prove their tight- 
ness, liquid cement is run in until the space is com- 
pletely filled. 

It is now necessary to cover the tubes over with con- 
crete and weigh them down, protect them from the 



SUBMARINE TUNNELS. 433 

action of the water, and stiffen them. As a preparation 
for the concrete a two-foot layer of gravel is spread 
over the bottom of the trench, and then tons and tons 
of concrete are shot down between the diaphragms 
through tubes leading from mixers floating above. 
Stout planking, attached to the diaphragms so as to 
form long wooden walls along the outside of the sec- 
tion, gives a definite shape to the concrete mass, which 
is earried 5 feet above the tops of the tubes. The 
space between the planking and the sides of the trench 
is filled wi^'h clay, and the top of the whole is covered 
with stones. Fig. 222 is a section of the filled trench 
with tubes in position. 

As soon as the concrete has been hardened into a 
huge monolith, pumps are set to work to empty the 
tubes. The wooden bulkheads at the adjacent ends 
of A and B are broken down, and a is put into connec- 
tion internally with the shore section, the outer bulk- 
head of A forming the end of the tunnel for the time 
being. Further sections are added in a precisely 
similar manner. 

The steelwork of the tubes is but the shell of the 
tunnel. Inside it the concreting gangs form concrete 
linings 2 feet thick in the top half, and thickened 
out into square-cornered benches (see Fig. 222) in 

28 




Fig. 223.— 




Fig. 224. — The section lialf submerged. 
{From photos, in "Cassier's Magazine.''') 



1 



SUBMARINE TUNNELS. 435 

the lower half to afford footways for the railway men 
and for passengers in case of an accident. The clear- 
ance between the rails and the centre of the arch is 
18 feet. 

The tunnel has a total length from jDortal to portal 
of 7,960 feet, made np of 2,600 feet of steel snb- 
river tubing, and 5,360 feet of land tunnel. If the 
approaches to the tunnels be added, the total length 
of the works is 12,000 feet, or nearly 2% miles. 

For the land portions of the tunnel two shafts were 
sunk on each bank, one near the river's edge, the 
second halfway between the first and the portal, so as 
to enable excavation to proceed at eight points simul- 
taneously under cover of shields. The inland tunnels 
are lined with concrete, and will be illuminated with 
electric lamps. The river-edge shafts are to be re- 
tained and lined to assist in the ventilation of the 
tubes. '^ They will be clean, and well ventilated, 
and entirely free from the deadly coal gases which 
fill tunnels operated by steam locomotives. There 
will be no grim record of death in the Michigan 
Central Tunnel." * 

The gradient on the American side is 2 feet in 100 ; 
that on the Canadian side 1% in 100. 

* Gassier' s Magazine, xxxiii, 349. 



436 SUBMARINE TUNNELS. 

It is calculated that the enormous quantities of 
concrete consumed in this enterprise will require 
300,000 barrels of cement, 250,000 tons of screened 
gravel, and 1,000,000 barrels of sand, the last coming 
from a point 60 miles distant. When the tunnels 
and approaches are finished and the electric plant 
installed, the -train-ferry boats that have plied be- 
tween Detroit and Windsor for so many years will be 
needed no longer. 



Chapter XXI. 
MINING AND MINES. 

Various types of mines — Shaft sinking — The Kind-Chaudron system 
— The freezing process adopted for sinking through quicksands 
— Fitting up the shaft — Hoisting gear — Ventilation — Natural 
circulation of air — Furnace ventilation — Fan ventilation — Un- 
watering a mine — By tunnels — By siphons — By ejectors — By 
buckets — By pumps — Breaking ground — Underhand and over- 
hand stoping — Timbering — The Lake Superior iron-ore mines — 
Two methods of working them — The Kimberley diamond mines 
— Coal mining — Laying out a coal mine — Post-and-stall method 
of getting out coal — Longwall mining — Coal-cutting machinerj^ 
— Hauling out the coal — Various systems employed — Hoisting 
the wagons ; time-sa\'ing devices. 

AS civilization depends so largely on tlie metals 
and minerals wliicli are extracted from the 
earth, the profession of the mining engineer is one of 
ever-increasing importance. We mav, therefore, well 
spare a chapter for a brief review of the various 
operations which are performed in the hunt for the 
hidden treasures of the earth. 

As prospecting for minerals does not concern us, 
we must dismiss it with a word. A deposit, seam, or 



438 



MINING AND MINES. 



reef may be found at a point where it " outcrops " — 
that is, comes to the surface — or it may be discovered 
only after laborious probing of the earth with diamond 
and other drills. 

Mines are of many kinds. Some take the form of 




Fig. 225." — Air-drills at work in the Rand mines. 
{Photo, Ingersoll Sergeant Drill Co.) 

mountains of ore which can be dug away bodily with 
steam shovels. Others are merely large bodies of 
mineral in the ground, easily accessible after a layer 
of ^^ overburden " — useless earth — has been removed. 
Or, as in the case of the South African gold mines, 



MINING AND MINES. 



439 



ore may exist in thin reefs^ more or less vertical; 
while the majority of coal mines have comparatively 
horizontal seams, reached either throngh very deep 
shafts or throngh sloping tunnels. Finally, a single 
mine may have to be 
worked at different stages 
in its history by several 
different methods. 

SHAFT SINKING. 

A very large proportion 
of mines are entered 
throngh vertical shafts, 
sunk in some instances to 
enormous depths. The Red 
Jacket shaft of the Calu- 
met and Hecla copper 
mine is nearly a mile deep, 
and its construction re- 
quired the removal of 
1,500,000 cubic feet of 
rock. In hard ground, free from water, a shaft is 
usually of rectangular section, but in the presence 
of water, or where it has to withstand great pressure, 
it is cylindrical. The lining is of wood, masonry, 
or iron plates — ^most commonly the second. In Fig. 




-Lining a shaft with 
masonry. 



440 MINING AND MINES. 

226 we see masons at work. The shaft is sunk and 
lined a section at a time, a ledge being left at the 
bottom of each lowest section to support it while it 
is built up to join the section above. The interven- 
ing ledge is broken away piecemeal to allow the 
masonry to be bonded together. A suspended plat- 
form carries the masons, and is raised as the work 
proceeds. 

In v\^ater-bearing strata special methods must be 
adopted. To moderate depths the pneumatic caisson 
may be sunk in the manner described in connection 
with the shafts of the Rotherhithe Tunnel. For 
depths at which the requisite air-pressure would be 
greater than men could endure, a huge boring tool is 
used to make a '^ pilot " shaft 4 or 5 feet in diameter, 
which serves to guide a somewhat similar but much 
larger tool that drills out the shaft to full size. 

The sinking completed, the lining of circular 
flanged iron rings, bolted together by the flanges, is 
lowered. As the bore is quite smooth from top to 
bottom the lining would become unmanageably heavy 
when a considerable number of rings had been 
assembled, unless the engineers pressed the water 
which has compelled them to adopt the Kind- 
Chaudron process — as it is called — into their service. 



MINING AND MINES. 



441 



The lowermost rings are provided with a " moss box " 
which prevents water passing between the lining and 
the sides of the bore. I^ear the bottom the lining is 
spanned inside bj a watertight diaphragm, from the 
centre of which a tube leads to the surface. 
This arrangement 




converts the lining 
into a gigantic piston 
or plunger, which can 
sink down the shaft 
only if the water be- 
low the diaphragm is 
allowed to escape 
through the central 
tuh , so that the en- 
gineers have complete 
control over the 
weight. When the 
bottom has been 
reached the space between the lining and the ground 
is filled in with liquid hydraulic cement, and the 
water is pumped out. The freezing 'process is em- 
ployed for sinking through very unstable strata, 
such as quicksands, in the following manner. A 
number of bore holes are marked off in a circle sur- 



FiG. 227. — Diagram to explain how a 
point c is transferred from the surface 
into the workings of a mine. Four 
guides are fixed at the top of the shaft 
at A B D E^ on lines which meet at c. 
Plumb-bobs hung from the guides to the 
bottom make it easy to find a point 
vertically below c. 



442 MINING AND MINES. 

rounding the site of the shaft, sunk to a depth at 
which solid ground is reached, and lined with iron 
tubes. These tubes then have lead plugs forced down 
to the bottom to keep water out, and into them are 
introduced much smaller tubes with open lower ends. 
A freezing mixture pumped down the inner tubes 
returns between them and their respective outside 
tubes to the surface, where it is again cooled to a very 
low temperature. In the course of a few months the 
earth, sand, etc., for a considerable distance round the 
tubes is frozen solid, and is kept in that state while 
th3 shaft is excavated and lined in the manner usual 
for firm ground. One of the most remarkable in- 
stances of the successful application of this process 
is that of a colliery shaft sunk 484 feet through a 
quicksand. In the shaft bottom the frozen sand was so 
hard that blasting had to be continued through the 
deposit. The temperature was here 14 degrees below 
zero, Centigrade. To thaw the frozen ground warm 
brine is circulated through the pipes. 

FITTING UP THE SHAFT. 

The shaft, whatever be its section, is, if a working 
shaft, divided vertically into several compartments by 
continuous bulkheads, usually of timber. Two at 



MINING AND MINES. 443 

least, sometimes four, are reserved for hoisting, and 
fitted with rails to guide the cages as they flv up and 
down. Another compartment belongs to the ventila- 
tion equipment; another accommodates pump rods, 
water-pipes, electric cables, etc. 

At the shaft bottom are situated offices, pumping 
stations, and machinery for compressing air and haul- 



FiG. 228. — Compressed-air locomotive for use in mines. 
{Photo, Baldwin Loco. Co.) 

age purposes. In a coal mine the coal is left un- 
touched for a considerable distance round the bottom 
— the '^ pit's eye," the miners call it — so that no 
injury may be caused by a settlement to this most 
vital part of the workings. 

HOISTING GEAK. 

The slow and steady progress of an ordinary pas- 



444 MINING AND MINES. 

senger lift would be far too slow for mining work. 
It may come as a surprise to the reader to learn that in 
some very deep shafts the cages move at the rate of 
35 miles an hour — a fair train speed — while 20 miles 
an hour is quite common practice. The individual 
loads raised scale many tons, and to rush them up 
" to bank '' requires enormously powerful engines and 
very strong overhead gear and ropes. The overhead 
gear, just mentioned, is a prominent feature of a 
mine, with its towering trestle and pair of huge rope 
wheels revolving in opposite directions, as one cage 
rises and the other sinks. The ropes, wound off from 
and on to huge drums in the engine shed, are generally 
made of many steel wires twisted together, and in 
some cases increase in thickness towards the upper 
end, as the fully unwound rope has to sustain its own 
weight as well as that of the cage and its load. Where 
very long ropes are used they form the larger part of 
the total weight to be raised by the engines. 

VENTILATION. 

Most mines are provided with at least two shafts, 
to give a good circulation to the workings. A shaft 
through which air descends is named a ^^ downcast;'' 
one in which it rises, an ^' upcast." 



MINING AND MINES. 



445 



Natural circulation is created if the two shafts have 
their upper ends at different levels, as in Fig 229. 
In summer, when the outside atmosphere is 
warmer than the air in the mine, b would 
be the ^^ upcast," and a the ^^ down- 
cast," because the cold column of air 
in A is heavier than the shorter 
column in B. In winter, 
when air is warmer be- 
low ground, than 
above, the buoyancy 
of the air in a would 
overcome that of the 

Fig. 229.— System of natural ventilation. air in B^ and tllC re- 

spective functions of the two shafts would be reversed. 
Natural ventila- 



tion is erratic, how- 
ever, and not to be 
depended on. In 
coal mines, where 
fuel is at hand in 
plenty, furnace ven- 
tilation is found 
convenient. A fur- 
nace chamber (Fig. 





Fig. 230. — Ventilation by furnace draught. 



446 



MINING AND MINES. 



230, c) is made near the foot of the " npcast," a, to 
which it is connected by a short inclined shaft. The 
hot gases rise through this to the surface, and fresh air 
__, , - ^ rushes to the furnace 



Fig. 231. 



-Plan of air circulation system 
in mine. 



to take their place, 
after circulating from 
the ^^ downcast," h, 
through the mine. In 
rig. 231 dddd are 
'^cross-overs," the pur- 
pose of which is ob- 
vious. The arrows in- 
dicate the direction of the air currents. A '^ blind " 
heading or gallery, e, is ventilated by erecting a 
central partition of cloth, wood, or brickwork almost 
to the end, so as to compel the air to penetrate it on 
its way to the furnace. 

The ventilation of a coal mine with its hundreds of 
passages is a somewhat complicated matter. Fig. 232 
illustrates the system of building permanent stopingr 
(a a) in those passages which are no longer in use, 
and fitting double doors (b b) in those along which 
men and trucks have to pass to divert the air in the 
desired direction. The double doors form air-locks, 
one door always being shut, and are so arranged that 
a truck opens and closes them automatically. 



1 



MINING AND MINES. 



447 



Fan ventilation is now the favorite practice with 
mining engineers. A huge fan, either belt-driven or 




Fig. 232. — Ventilation of a coal-mine. AAA are " stopings " to guide air in 
the required direction ; b b are double doors for communication. 

coupled up direct to a turbine, is erected in a chamber 
at the top of one of the shafts (Fig. 233), through 
which it sucks or 
drives vast quantities 
of air. 

In a well-ordered 
mine a plentiful sup- 
ply of air is taken to 
the remotest corners 
in which men are at 
work, even though 
they be miles from 
the shafts. The cur- 
rent keeps the miners Fig. 233.— ventilation by fan. A fan placed 
IT 14-1^ 1 ill a chamber connected with the upcast 

in good lieaitil, and sucks the foul air out of the workings. 




448 MINING AND MINES. 

also removes what miglit be dangerous accumulations 
of fuul and explosive gases; the last being met with 
most frequently in coal mines. 

UNWATERIXG A MINE. 

Freeing a mine of water is one of the most trouble- 
some problems that mining engineers have to solve. 
In some mines the weight of water removed far ex- 
ceeds that of the mineral or ore — for example, in the 
Westphalian coalfield about 3 tons of water are lifted 
out to every ton of coal; and in Staffordshire the 
proportion has even reached 28 tons of water per ton 
of coal. AYherever possible, natural drainage by 
gravitation is used. A tunnel is driven on a gentle 
incline through the side of the hill into the bottom 
of the workings, so as to tap the water at a low level. 
Even when the mine is sunk below the tunnel, the 
latter is valuable, as water has to be lifted through a 
comparatively small height for discharge. 

Some wonderful drainage tunnels are in existence, 
the most famous of them the Sutro Tunnel, driven 
through 4 miles of rock into the great Comstock 
Silver Lode, ISTevada, at a cost of over $7,000,000. 
In the Claustal Mines in the Harz Mountains is a 
10-mile tunnel; at Freiburg one of 8 miles; and at 



MINING AND MINES. 



449 



Sdiemnitz the Emperor Joseph Adit burrows for 9 
miles. All these are far exceeded by the Great County 
Adit in Cornwall, which, with its various branches, 
totals 30 miles. In Wales a drainage adit pours out 
15,000,000 gallons by gravitation every twenty-four 
hours. 




Fig. 23-i. — Diagram to show siphon and ejector systems of unwatering a mine. 

If the tunnel rises towards the entrance or changes 
level, as in Fig. 234, a siphon pipe is used. The 
principle is explained in detail by Fig. 235, wherein 
a is the suction pipe and h the delivery pipe. A 
small tank, c, is fitted with a footvalve, Avhich opens 

29 



45° 



MINING AND MINES. 



^: 



ji 






upwards, to allow air to escape from the pipe while 
it is being charged. One of these valves is fixed at 
the highest point in the siphon 
wherever the pipe takes a down- 
ward conrse. (See Fig. 234.) 

In Eig. 236 is illustrated an- 
other drainage method, by a ivater 
ejector. (See also Fig. 234.) A 
pipe, e, leads from a tank, d, over 



Fig. 235. — Siphon with 
foot-valve to allow air 
to escape when the 
siphon is charged. 



ll-d 



m 



1'^'^^^ 
i«>^ 



the shaft-head down to near the 
snmp r at the bottom, where it 
turns upwards and is continued 
as a rising main, f, to discharge 
at the surface. A short branch 
pipe, h, dips into the sump, and 
has at the point of junction a 
nozzle, i, pointing upwards inside 
pipe /. The uj)ward velocity of 
water through / past the nozzle 
draws water from the sump by 
suction and carries it, as well as 
the water from the tanlv d, to the 
surface. 

Another method is to lower a large cylindrical 
bucket by a winding gear into the sump, and draw 



.'j 



h 

7^~ ; 



Fig. 236. — A water ejec- 
tor. 



MINING AND MINES. 



451 




it lip when it has filled itself through a valve, k, which 
opens when the bucket rests on the bottom of the 
sump (Fig. 237). 

Finally, there is the ejection of water 
by large pumps stationed at the bottom of 
the shaft, and operated either by electric 
motors, fed with current from a power- 
house above ground, or by long rods work- 
ing up and down in guides in the shaft. 

BREAKING- GEOUXD. 



^^ 



Fig. 237. — 
Self -filling 
bucket for 
lifting wa- 
ter from a 
mine. 



We may now proceed to a short descrip- 
tion of the getting out of minerals. 

Fig. 238 serves to explain some of the 
most common mining terms. The solid 
black portions b b indicate seams or veins of the pay- 
ing material mined for ; a a the enclosing rock and 
clay. A shaft, c c c^ is sunk through a a^ clear of the 
vein if possible, and from it, at regular intervals, 
levels, galleries, or drifts, d d^ d r^ are cut horizontally 
to and through the vein. Vertical passages, e, called 
winzes, connect the levels, and so divide the veins into 
rectangular blocks, named stopes. The cutting away 
of these blocks is called stoping. There are two meth- 
ods of stoping, the '' overhand " and '^ underhand." 



452 



MINING AND MINES. 



Overhand stoping is seen in progress at k. The 
miners begin operations at the bottom of a stope near 
a winze, and hack at the roof. The stuff broken awaj 
gives them a foothold that rises with the roof. Event- 
ually all the paying stuff is dropped through ^^ rises," 
or openings in the pile, into trucks in the gallery be- 
neath. ^ 




^S^^^S^^^^^ 



Fig. 238. — General section of mine, to explain mining terms. 

Underhand stojDing, shown at l, is the reverse 
process. The miners attack the stope at the top and 
work downwards, throwing the ore, etc., on to plat- 
forms of '^ stull-jiieces," from which it is raised in 
buckets to the level above, or thrown down through 
a shoot into wagons below. 

o 



MINING AND MINES. 



453 



Eubbish is separated from paying stuff and nscd 
to fill in the stopes with as they are worked out. In 
some cases it is necessary to bring down filling ma- 
terials from the surface. 

Where a very large mass of ore is encountered, the 




Fig. 239. — Timbering in a mine gallery. 

gradually rising roof is held up by an elaborate 
system of timber-framing rising tier upon tier. In 
the Comstock mines one chamber was 400 feet from 
floor to dome, and whole forests were felled to supply 
the timber needed for the work. 



454 



MINING AND MINES, 



The galleries of a mine are timbered (see Fig. 239), 
and in places even lined with masonry. To drive 
them, blasting is used as in ordinary tunnelling. The 
power-drill, which does the work of a score of hand- 
drills (a bar struck with sledge-hammer, and partly 




Fig. 240.- — A Bucyrus steam-shovel at work moving iron ore, 

revolved between every two blows), effects most of the 
boring in many mines, and greatly reduces the wages 
bill. 

THE LAKE SUPERIOR IRO^N'-ORE MINES. 

Within a hundred miles of Lake Superior lie the 



MINING AND MINES. 455 

great iron-ore deposits of Xortli America. The 
Gogebic, Vermilion and Mesabi ranges of bills in 
tbis district contain hundreds of millions of tons of 
ore. At many points tbe ore is scooped ont into 
trucks by great steam-sbovels (see Fig. 2-10), wbicb 
will load 800 to 1,000 trucks an bour for weeks 
together. Elsewhere tbe deposits are worked verti- 
cally by several methods, two of which are shown in 
Figs. 241 and 242. Take Fig. 241 first. A shaft 
is sunk through the adjacent rock, and a cross-cut 
is driven into the ore. On both sides of tbis branch 
out galleries, yy (see the plan). Small shafts, or 
shoots, X X, are then sunk into these galleries, and 
down them the miners throw the ore into trucks, which 
carry it away and dump it into large buckets plying in 
the shaft. Before the first level is reached, another 
cross-cut and its galleries and shoots have been made 
ready for the removal of another layer; and the 
process is repeated until the deposit has been worked 
out. 

Should the overburden be too thick to be removed 
profitably another system is adopted (Fig. 242). Two 
levels are driven, the uppermost immediately below 
the overburden, and connected by shoots, s s. Level 
^"0. 1 is widened out and lengthened, all the ore being 




• 



Fig. 241. — ^Elevation and plan of a method of mining used in the iron-ore 

mines, Lake Superior region. 

{From an illustration in " Cassier's Magazine.") 



MINING AND MINES. 



457 



shot down to the level below, whence it is transported 
to the shaft. When the ore of the slice has been 




^^^^^^^^^^^^^^^^ 




Fig. 242. — Another method of mining iron ore. 
(.From an illustration in " Cassier's Magazine.") 

removed in this manner, the props supporting the earth 
are blasted awav, and the roof allowed to fall in on 
the floor. Another level is then driven immediately 



458 



MINING AND MINES. 



below 'No. 1, the floor of which serves as the new roof, 
and a second slice is excavated. In this Avay the whole 
block down to Level 2 is removed, and it then be- 
comes necessary to drive Level 3 and put up fresh 
shoots to Level 2 before operations can be continued. 




^^BLUE CROUNC 

.^..'r.°:.'-///.'-.i....^ 

Fig. 243. — Section of a diamond mine. After some of tbe " blue- ground " has 
been excavated from tbe surface a sbaft is sunk and the deposit attacked 
from below. 

This method has the advantage of keeping the 
weight on the roof — that is, the weight of the over- 
burden — constant. It is applied, in a modified form, 
to the Kimberley diamond mines, South Africa (Fig. 
243). These mines were worked at first as '^open- 
cast;" but when the depth became too great for con- 



MINING AND MINES. 459 

venience a shaft was sunk, and the diamond-bearing 
^' blue-gronnd " (a species of rock) attacked from 
below, the rubbish being allowed to remain in the 
^^pipe" as an increasing overburden. 



COAL MINING. 

The extraction of coal from the seams in which it 
has formed during the course of ages is the most 
important of all mining industries. In the year 1907 
the total quantity of coal raised in the United States, 
Great Britain, Germany, France, and Belgium ex- 
ceeded 800,000,000 tons. Of this about one-half was 
mined in the United States, where the annual con- 
sumption of the mineral averages 4I/2 tons per head 
of the population. The United Kingdom requires 
about 4 tons per head. 

Coal occurs in seams from a few inches to 100 feet 
ii\ thickness, and as a consequence coal-mining prac- 
tice includes several different methods of " winning '' 
the material. In Great Britain the vast majority of 
coal mines are worked through vertical shafts, sunk 
in some instances to depths exceeding 2,500 feet, from 
which passages are driven through the coal on a 
systematic plan. In the United States, especially in 
the " soft " or bituminous coal regions, a great deal 



46o MINING AND MINES. 

of the mineral is won through horizontal or incline;! 
tunnels (see ii and g in Fig. 238), and through 
'^ slopes/' which are shafts dipping at a considerable 
angle to the vertical. 

LAYING OUT A COAL MINE. 

There are two main methods of removing the coal. 
The first of these consists of cutting parallel galleries 
in directions at right angles to one another, so as to 
divide the seam into a number of rectangular blocks, 
which correspond in a horizontal plane to the vertical 
'^ stopes " of an ore vein. These blocks, known vari- 
ously as '' pillars," '' posts," and '^ banks," are robbe.i 
in regular order either from the boundary of the mine 
towards the shafts, or from the shafts towards the 
boundary. In the latter case roads for haulage and 
access- have to be left in the ^^ goaf ^' or " gob," as the 
rubbish is called with which the excavated chambers 
are filled (see a in Fig. 244). The system just 
described is termed the '^ post and stall," or '^ pillar 
and stall " system, the word stall signifying the pas- 
sages which surround the pillars. In former times 
part of the pillars was left to hold up the roof, but 
nowadays the coal is robbed completely. 

In thin seams of four feet and less in thickness the 



MINING AND MINES. 



461 



longwall method is more generally employed. A 
comparatively few passages are driven, and the coal 
is attacked on long faces, as shown in Fig. 245. As 
in the first method mentioned, progress may be either 
outwards or inwards, or in both directions simnltane- 





COAi-^t'-ve..) 



^^^■■■■■■■■■■■■■■■■■■il 






■■■■■■■■■■■■■■■■■■■■■gr^: 




,.0-::::;::^^. 






Fig. 244. — Plan of coal-mine worked on the " post and stall " method. 

The two small circles are shafts. 
Fig. 245. — Longwall mining. 
Fig. 246. — A longwall miner midercutting the face. 

ously in different parts of the mine, to keep the 
average distance of hauling as constant as possible. 

The longwall miner undercuts the face to a depth 
equal to the thickness of the vein, so as to form a 
groove at the bottom of tlie seam (Fig. 24G). The 
coal is supported by short wooden sprags, so that the 
miner may run little risk of being crushed by a fall. 



462 MINING AND MINES. 

When the length has been ^' holed/' the sprags are 
knocked out, and if the coal does not fall by its own 
weight holes are drilled in the top of the seam and 
it is blasted down. 

CUTTING MACHINEEY. 

For longwalling in soft coal mechanical cutters are 




Fig. 247. — A machine for undercutting coal, c c c are cutters attached to the 
circumference of a wheel revolved by compressed air or electricity. 

now widely employed, especially in the United States. 
These machines are of many types. One resembles 
a horizontal circular saw (Fig. 24Y), with cutting 
chisels set at regular intervals round the circumfer- 
ence of a wheel five feet or more in circumference. 
Another variety has a long revolving toothed bar, 
w^hich saws through the coal much like an ordinary 
saw. There is, too, the machine with a spiked chain 



MINING AND MINES. 463 

passing round the end of a long arm; and a device 
which imitates the action of a miner striking with 
a pick. 

These machines travel on rails laid parallel to the 
face of the coal, and are driven by compressed air or 
electricity. One machine will do the work of from 
fifteen to twenty men, and with less waste of coal. 
Furthermore they relieve the miners from doing ex- 
tremely hard labor in very cramped attitudes. 

HAULING OUT THE COAL. 

In shaft mines two main haulage roads are run 
from end to end of the workings. Each road is 
equipped with a single or, where the quantities moved 
are unusually great, with a double rail track. In 
either ^ase, arrangements are made to keep the full 
trucks moving towards the shaft on a separate track 
from that by which the empty trucks return. From 
the main track side tracks branch out. These are 
frequently operated by boys who push the trucks up 
to the main line, where they are coupled up with the 
haulage ropes. 

The ropes are driven by an engine near the pit 
bottom. A rope passes from one drum to the end of 
the track, round a large horizontal pulley, and back 



464 



MINING AND MINES. 



to a second drum. The drums turn in opposite 
directions, and the one takes in the rope as fast as 
the other pays it out ; or an endless rope is kept mov- 
ing continuously in one direction. Trucks can be 
hitched to the ropes at any point. 

In Fig. 248 we have instances of roads running up- 
hill in the one case (a) and 
downhill in the other (h). In 
a it is necessary to use a tail 
rope passing round pulley c to 
draw the empties back to the 




Fig. 248. — Hauling wagons to the foot of a shaft. 

working, unless the haulage be so arranged that the 
full cars running down pull the empty cars back on a 
separate track. 

On a downhill track the cars return to the working 
by gravity, and power is needed only to bring them 
to the shaft. 

In Fig. 24-0 we see the method of operating a side 
road, /, :J^ combination with the main road. To draw 



MINING AND MINES. 465 

trucks from the branch, the main road ropes are 
nncoupled at e e and hitched on to those in /. Any 
number of branch roads can be worked in this way. 
In mines entered through a horizontal tunnel, haul- 
age locomotives are often found very useful and conven- 
ient. These locomotives are propelled either by com- 
pressed air stored in a large boiler-like cylinder (Fig. 
228) or by electric current ^.^^^ 

picked up by a trolley arm from ^x^^ 



^y^-\^^fea:3azHiii ---^ . - . ,. - -^ 

Fig. 249. — Diagram to explain liow a branch track is worked iu combination 
with the main track in mine galleries. 

an overhead cable. An illustration is given (Fig. 250) 
of an electric locomotive emerging from a mine with 
its train of trucks. 

We may conclude this chapter with a notice of 
the manner in which skips are put on board hoisting- 
cages and removed from them with the least possible 
delay. The lift has several stories for as many tiers 
of trucks. At the pit bottom there is a hydraulic 
lift with floors to correspond with those of the cage. 
The lift is lowered, and a few trucks are shoved on 
board. It rises till the second floor is on a level with 
the rails and receives a second batch, and so on till 



466 



SUBMARINE TUNNELS. 



it lias its full load. When the cage descends the empty 
trucks are discharged into a second lift, which trans- 
fers them in hatches to the rails, and the full trucks 
are pushed in, all tiers simultaneously. At the top 




Fig. 250. — An electric locomotive hauling a train of trucks from a mine adit. 

of the shaft is a similar installation, which clears the 
cage of full trucks and loads it with empties. Thus 
no time is wasted, as the lifts are being filled and 
cleared while the cage is travelling in the shaft. 

[Note. — Any reader who is specially interested in mining should 
consult "The Romance of Mining," in which are given full accounts of 
many of the world's greatest mines, and a more detailed description of 
their working than could be included in this chapter.] 



Chapter XXII. 
POWER FROM FALLING WATER. 

The pressure of water — The wasted energy of Niagara Falls — Early 
attempts to use it — Great development — ^An industrial Niagara 
— Great installations — Facts about power companies at Niagara 
— Method of generating power — The Ontario Power Co. — Huge 
water-pipes — A relief weir — Types of turbines — A monster tur- 
bine — Future development of water power — High-pressure water 
power. 

I!N^ many towns the pressure of the water supply 
is such that if you press your thumb against 
the nozzle of a house tap and open the valve the 
water will force its way out in angry spurts. Whence 
comes this power ? From the weight of the water. 
If the surface of the reservoir which feeds the main be 
100 feet higher than the tap, your thumb has to sup- 
port a column of water 100 feet high, having a section 
equal to the area of the hole in the nozzle, and weigh- 
ing about 45 lbs. to the square inch. Were the tap- 
water directed into a turbine of suitable size, it would 
generate sufficient energy to light several electric 
lamps. 

The amount of water that issues from a tap is very 



468 POWER FROM FALLING WATER. 

trifling as compared with that which passes over manv 
a waterfalL At Niagara a solid wall of water, 2 'J 
feet deep, representing 275,000 cubic feet per second, 
thunders 200 feet into the abyss. Expressed in terms 
of energy, Niagara Falls develop 7% million con- 
tinuous horse-power — more in a year than that which 
would be produced were all the anthracite coal mined 
annually in the United States consumed in the furnaces 
of steam boilers. 

For centuries this prodigious energy has been ex- 
pending itself in carving a deep, narrow chan- 
nel through the rock that separates Lakes Erie- 
and Ontario. Man first feared the magnifi- 
cent waterfall; then he admired it; and now, 
in an age when the useful often has to take 
precedence of the beautiful, he seeks to force some 
of this natural power to serve his ever-increasing 
needs. 

As long ago as 1725 a saw-mill wheel — a crude 
and imperfect contrivance — was set up at the edge of 
the Falls. The growth of the steam engine in the 
early half of the nineteenth century retarded the 
development of an industrial Niagara, and not until 
1870 was the problem of utilizing the Falls' inexhaust- 
ible power seriously attacked. In 1886 a syndicate > 



POWER FROM FALLING WATER. 



469 



secured from the l^ew York Legislature a concession 
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Fig. 251. — View of power-transmission lines. 
{Photo, Ontario Power Co.) 

200,000 horse-power. People wondered what use 
could be found for even a tenth part of this. The 



470 POWER FROM FALLING WATER. 

syndicate went ahead. To-day 400,000 electrical 
liorse-power is generated by turbines within a few 
hundred yards of the Falls, and provision has been 
made for installations which will in time raise the 
total to 900,000 horse-power. 

The result is seen in the growth of a great manu- 
facturing city on the American side of ^NTiagara, in 
wliich not a single steam-engine pants, though coal 
.is very cheap in the locality. Even in Buffalo, where 
coal costs only $1.50 a ton, electric power, trans- 
mitted 23 miles from the Falls, has completely ousted 
steam ; a fact which is not a matter for astonishment, 
considering that the generating companies supply cur- 
rent at the rate of $25 a year per horse-power 
running continuously. This works out at about one- 
third of a cent per hour. It may well be asked, who 
would do the mere shovelling of coal into a furnace 
for this money ? Every year the great electrical 
tentacles reach out further and further, and grip town 
after town. Already the street cars of Syracuse on the 
east and of Toronto on the west — 250 miles apart — are 
operated by Magara power, as is also a section of the 
Erie Railroad, 150 miles distant. Within a few years 
towns 300 miles away will be tapping the energy of 
the great Falls. 



POWER FROM FALLING WATER. 471 

FACTS ABOUT THE POWER-HOUSES. 

The chief installations running at Niagara are: — 

On the American Side. 

1. The ^Niagara Falls Power Co., with two power- 
houses developing 105,000 h.p. 

2. The ISTiagara Falls Hydraulic Power and Manu- 
facturing Co. ; 65,000 h.p. 

On the Canadian Side. 

S. The Magara Falls Canadian Power Co., de- 
signed to generate 110,000 h.p. with 11 dynamos. 

4. The Electrical Development Co. ; 125,00 h.p. 

5. The Ontario Power Co., for 180,000 h.p. 

Of these N^os. 1 and 3 are owned by the same cor- 
poration, and are connected through cables carried 
across the gorge on one of the bridges that span it. 

METHOD OF GENERATING POWER. 

The difference in level between the upper river and 
the rapids below the Falls is about 200 feet. The 
turbines are in all cases situated 170-180 feet below 
the surface of the upper river, and the water is 
supplied to them through penstocks, or vertical pipes, 



472 



POWER FROM FALLING WATER. 




the largest of which 
are 11 feet in diam- 
eter. The instal- 
lations 1, 3, and 4 
have deep wheel- 
pits cut in the rock 
above the Falls for 
the penstocks and 
turbines, the latter 
revolving long 
shafts which carry 
the moving parts of 
generators sta- 
tioned in power- 
houses on the sur- 
face of the ground 
(Fig. 252). To get 
rid of the water 
when it has passed 

Fig. 252.— a wheel-pit in the Niagara Falls thrOUgh the tur- 
Power Co.'s installation, g = generator; 

s = shaft; t = turbine; p = penstock. biueS, tunucls haVC 
The pit is 178 feet deep. 
(From an illustration in'' Cassier's Magazine.") beCU drlvCU thrOUgh 

the rock on a gentle gradient to points below the Falls. 
The tunnel, or ^^ tail-race/' of the ^^iagara Falls 
Power Co. is 7,000 feet long, with a maximum sec- 



POWER FROM FALLING WATER. 



473 



tion of 21 feet by 18 feet 10 inches. The driving of 
this tunnel occupied 1,000 men continuously for three 
years; required the removal of 
300,000 tons of rock; and con- 
sumed 16,000,000 bricks for its 
lining. Add the quarrying out 
of 123,455 cubic yards of rock 
for the wheel-pits, and you 
realize that here a very consid- 
erable engineering feat has been 
performed. 

The method preferred for in- 





FiG. 253. — Diagram of power-house of the Niagara Falls Hydraulic Power and 
Mauufaciuring Co., showing penstocks carried down the cliff from the 
canal to the turbines. 

stallations 2 and 5 was to build the power-houses he- 
low the Falls, and to lead water through great cov- 
ered pipes, or through canals in the banks of the upper 
river to penstocks affixed to the face of the cliffs. Fig. 
253 is a sketch of the penstocks and power-house of 



474 POWER FROM FALLING WATER. 




Fig. 254. — Laying an 18-foot flume in Victoria Park, Niagara Falls. 




Fig. 255. — Tlie flume partly encased in concrete before tlie tieucli is filled in. 
(Plioios, The Ontario Pouer Co.) 



POWER FROM FALLING WATER. 475 

the l^iagara Falls Hydraulic Power and Manufactur- 
ing Co. Tliis system obviates the need for a costly 
tunnel and deep wheel-pits. All the work done is 
surface work. 

By the courtesy of the Ontario Power Co., I am 
enabled to give illustrations of the process of laying 
one of the three great 18-foot steel flume pipes which 
will ultimately supply their power-house. About a 
mile above the Palls a great wall about 600 feet long 
has been built out obliquely into the river, slanting 
down stream, l^ine feet below the water level it is 
pierced by a number of sluices, controlled by gates, 
through which water enters the forebay. Prom the 
end of the intake wall a submerged spillway slants 
away to the shore; so that a triangular area is en- 
closed by the shore, the intake, and the spillway. As 
the intake makes a very acute angle with the general 
direction of the current, it affords no lodgement for the 
ice which floats down plentifully in winter and early 
spring. 

Prom the main forebay the water passes into an 
inner forebay, excavated in the bank, through a second 
intake also provided with deep-level sluices, and so 
reaches the gate-house, where are entrances to the 
three flumes, one of which is completed. Any ice 






I 



POWER FROM FALLING WATER. 477 

that may have penetrated to the inner forebay is kept 
out by wicle-mesh screens. 

The flume, 18 feet in diameter and 6,500 feet long, 
is laid in a deep trench and covered over with con- 
crete and earth, so as not to disfigure the scenery of 
the Victoria Park, through which it passes. Arriving 
at the cliff below the Falls, it throws out on the under 
side six 9-foot penstocks (see Fig. 257), carried down 
in pairs through vertical shafts and horizontal tunnels 
cut in the solid rock to the turbines of the generating 
station, built on a ledge 20 feet above the level of the 
lower river. The turbines are mounted horizontally 
in pairs on the same shaft as a single generator which, 
at 187% revolutions a minute, has an output of 
11,400 electrical horse-power. Fig. 256 shows one of 
the twenty ^^ units '' with which the power-house will 
be equipped ultimately. The man seen between the 
generator and a turbine affords a standard by which to 
judge the dimensions of the machinery. 

The current generated is taken through cables laid 
in inclined tunnels cut in the cliff up to a large dis- 
tributing station built on an elevation 250 feet above 
the turbines. An interesting feature of the hydraulic 
engineering needed for the work is the relief weir 
(see Fig, 257) at the penstock end of the flumes. To 



478 



POWER FROM FALLING WATER. 



prevent an undue strain on the flume when a penstock 
valve is closed, the water is allowed to rise up an in- 
clined orifice and fall over 
a weir into a drain that 




Fig. 257. — Section of relief weir at end of flume. When a penstock valve is 

closed, undue pressure is prevented by the water rising over the weir. 

(.Photo, The Ontario Power Co.) 

leads it away to the river. As soon as the temporary 
pressure is relieved the water subsides behind the weir 
to its normal level. 



TYPES OF TURBINES. 

Water turbines are of two main types: (a) Axial 
floiv turbines ; (b) radial flow turbines. 

An axial flow turbine resembles in principle the 
ordinary windmill. The water travels in the direction 
cf the axis of the shaft, and moves sideways the vanes 
attached at right angles to the shaft. In radial flow 
turbines the water moves towards or away from the 
shaft through vanes set in rings attached to the shaft. 
In all cases fixed guides are used to make the water 
strike the moving vanes at an effective angle. 



POWER FROM FALLING WATER. 



479 



The Niagara installations have axial flow turbines. 
In the E'iagara Falls 
Power Company 
plant, where the tur- 
bines are at the bot- 
tom of a deep pit, 
they are so designed 
that the upward 
pressure of the water 
in each turbine shall 
support the thirty- 
five tons weight of 
the shaft and re- 
volving portion of 
the generator. The 
water passes from 
the penstock into a 
barrel-shaped cham- 
ber, and spurts out ^^^- ^f^' 

^ ^ in the 

through rows of 
guide blades set 
around the circum- 
ference at the top 
and bottom. Immediately outside the barrel, oppo- 
site the guides, are vanes attached to two rings. The 




— Section of one of the turbines 
Niagara Falls Power Co.'s in- 
stallation. The revolving parts are 
marked in solid black, a = body of 
turbine ; b = fixed guides ; w^ w^ = 
rings carrying moving vanes ; g G = 
governor regulating the amount of wa- 
ter passed through the vanes ; s = 
shaft. 



48o POWER FROM FALLING WATER. 

water strikes these at an angle and causes the rings 
to revolve. These rings turn a shaft which penetrates 
both ends of the barrel. The top end of the barrel is 
pierced with holes, so that the water may press up- 
wards against the under side of the upper ring and 
support the shaft and its load. As the gland in the 
bottom of the barrel, through which the shaft passes, 
is water-tight, there is no downward pressure to 
counteract the upward thrust on the top ring. (See 
Fig. 258.) 

The Ontario Power Company, in common with two 
other of the big installations, employs turbines of the 
^' Francis '' type. The water enters a chamber sur- 
rounding the wheel, passes through guides, and strikes 
^V.G \\i3vin^ \iiiidh cquardy It is then deflected so as 
CO leave the turbine in the line of che etiait. I'Lis type 
is best suited for driving generators mounted on hori- 
zontal shafts. 

The largest single water turbine in existence is that 
installed at the Shawinigan Falls on the St. Maurice 
River, a tributary of the river St. Lawrence. The 
makers of this gigantic wheel, the I. P. Morris Com- 
pany of Philadelphia, have kindly furnished me with 
a fine illustration (Fig. 259), which will give the 
reader some notion of its size. It has a capacity of 




Fig. 259. — The largest water-turbine in the world, installed at the Shawingian 
Falls power-house. It develops 10,500 h.p. "Weight, 180 tons ; height, 30 
feet; width, 22 feet. In one minute 400,000 gallons of water flow through 
it. Made by the I. P. Morris Co., Philadelphia. 

31 



482 POWER FROM FALLING WATER. 

10,500 horse-power. It measures 30 feet from base 
to top, is 22 feet from back to front, and 27 feet 
wide between the bearings of the shaft. Its total 
Tveight is about 180 tons, 10 tons being accounted for 
by the shaft, a giant bar 22 inches in diameter. The 
rotatory part of the turbine is a 5-ton bronze casting. 
In one minute 400,000 gallons of water pass through 
the turbine w^hen it is under full load. This quantity 
would suffice to form a river 100 feet wide and 5 feet 
deep, flowing at a rate of about 1^ miles an hour. 

Progress in electrical science and the design of 
economical hydraulic engines seriously threaten the 
supremacy of steani as a motive power. In all 
civilized countries where there are waterfalls or 
mountain streams of large volume, the engineer 
is devoting his attention more and more closely to 
the work of harnessing the enormous forces of falling 
water. In many parts of the United States, Canada, 
Japan, E'orway, Sweden, Switzerland, Italy, France, 
Germany, Austria, and even in the United Kingdom, 
new water-power plants are being erected every month. 
We are as yet but on the edge of a revolution in 
our methods of capturing energy for locomotion, light- 
ing, heating, and factory operations. Many big 
rivers are still running free. In due course they too 



POWER FROM FALLING WATER. 483 

will contribute their quota of power to the use of man. 
At the present time a huge project is on foot for 
utilizing the Victoria Falls on the Zambesi. The Falls 
have a drop of about 400 feet, and the volume of water 
passing over them is far greater than that which drawls 
visitors to Niagara. Before many years have elapsed 
we shall hear of electric current being transmitted 
from the Zambesi to the gold mines on the Rand, 600 
miles away, and of the growth, near the Falls, of great 
manufacturing towns. The ^' smoke that thunders," 
as the natives name the mist rising from the gorge, 
will never be sullied by coal smoke, because fuel will 
not be needed for many miles around. 

HIGH-PIIESSUEE WATER POWER. 

The Niagara turbines use water that has a pressure 
at the foot of the penstocks of about 65 pounds to the 
square inch. At Manitou, Colorado, there is an in- 
stallation of Pelton water-wheels operated by water 
falling 2,417 feet, with a pressure of 1,000 pounds 
to the square inch. The water is collected high up on 
the mountain side, and descends through pipes to the 
generating station in the valley, whence, after turning 
the wheels and expending most of its energy, it passes 
into the to\\TL mains, and so serves a second and no less 



M 



484 POWER FROM FALLING WATER. 



useful purpose. So great is the strain on the pipes 
that ordinary lead joints could not be used, because 
the water simply squeezed out the soft metal. An 
alloy of tin and lead had to be substituted. The water 
issues from the nozzles at a velocity of 204 miles an 
hour in a bar that cannot be struck through with a heavy 
iron rod. Such a stream of water cannot be governed 
by throttling, as the slightest sudden check would 
wreck the pipes; so to meet variations in the load of 
the dynamos, the governors of the wheels are arranged 
to deflect the line of the nozzle below the buckets when 
less powder is needed, and to discharge the water into a 
long pool. If, for any reason, the valves have to be 
closed, the operation is performed through a gear 
which cannot completely cut off the water in less than 
twenty-five minutes. Even at this slow^ rate of re- 
tardation there is considerable extra pressure set up in 
the pipes. 



[Note. — For a full description of the Pelton wheel, see "How it 
Works," pp. 375, following,] 



THE END. 



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